a case study means

The Ultimate Guide to Qualitative Research - Part 1: The Basics

• Introduction and overview
• What is qualitative research?
• What is qualitative data?
• Examples of qualitative data
• Qualitative vs. quantitative research
• Mixed methods
• Qualitative research preparation
• Theoretical perspective
• Theoretical framework
• Literature reviews

Research question

• Conceptual framework
• Conceptual vs. theoretical framework

Data collection

• Qualitative research methods
• Focus groups
• Observational research

What is a case study?

Applications for case study research, what is a good case study, process of case study design, benefits and limitations of case studies.

• Ethnographical research
• Ethical considerations
• Confidentiality and privacy
• Power dynamics
• Reflexivity

Case studies

Case studies are essential to qualitative research , offering a lens through which researchers can investigate complex phenomena within their real-life contexts. This chapter explores the concept, purpose, applications, examples, and types of case studies and provides guidance on how to conduct case study research effectively.

Whereas quantitative methods look at phenomena at scale, case study research looks at a concept or phenomenon in considerable detail. While analyzing a single case can help understand one perspective regarding the object of research inquiry, analyzing multiple cases can help obtain a more holistic sense of the topic or issue. Let's provide a basic definition of a case study, then explore its characteristics and role in the qualitative research process.

Definition of a case study

A case study in qualitative research is a strategy of inquiry that involves an in-depth investigation of a phenomenon within its real-world context. It provides researchers with the opportunity to acquire an in-depth understanding of intricate details that might not be as apparent or accessible through other methods of research. The specific case or cases being studied can be a single person, group, or organization – demarcating what constitutes a relevant case worth studying depends on the researcher and their research question .

Among qualitative research methods , a case study relies on multiple sources of evidence, such as documents, artifacts, interviews , or observations , to present a complete and nuanced understanding of the phenomenon under investigation. The objective is to illuminate the readers' understanding of the phenomenon beyond its abstract statistical or theoretical explanations.

Characteristics of case studies

Case studies typically possess a number of distinct characteristics that set them apart from other research methods. These characteristics include a focus on holistic description and explanation, flexibility in the design and data collection methods, reliance on multiple sources of evidence, and emphasis on the context in which the phenomenon occurs.

Furthermore, case studies can often involve a longitudinal examination of the case, meaning they study the case over a period of time. These characteristics allow case studies to yield comprehensive, in-depth, and richly contextualized insights about the phenomenon of interest.

The role of case studies in research

Case studies hold a unique position in the broader landscape of research methods aimed at theory development. They are instrumental when the primary research interest is to gain an intensive, detailed understanding of a phenomenon in its real-life context.

In addition, case studies can serve different purposes within research - they can be used for exploratory, descriptive, or explanatory purposes, depending on the research question and objectives. This flexibility and depth make case studies a valuable tool in the toolkit of qualitative researchers.

Remember, a well-conducted case study can offer a rich, insightful contribution to both academic and practical knowledge through theory development or theory verification, thus enhancing our understanding of complex phenomena in their real-world contexts.

What is the purpose of a case study?

Case study research aims for a more comprehensive understanding of phenomena, requiring various research methods to gather information for qualitative analysis . Ultimately, a case study can allow the researcher to gain insight into a particular object of inquiry and develop a theoretical framework relevant to the research inquiry.

Why use case studies in qualitative research?

Using case studies as a research strategy depends mainly on the nature of the research question and the researcher's access to the data.

Conducting case study research provides a level of detail and contextual richness that other research methods might not offer. They are beneficial when there's a need to understand complex social phenomena within their natural contexts.

The explanatory, exploratory, and descriptive roles of case studies

Case studies can take on various roles depending on the research objectives. They can be exploratory when the research aims to discover new phenomena or define new research questions; they are descriptive when the objective is to depict a phenomenon within its context in a detailed manner; and they can be explanatory if the goal is to understand specific relationships within the studied context. Thus, the versatility of case studies allows researchers to approach their topic from different angles, offering multiple ways to uncover and interpret the data .

The impact of case studies on knowledge development

Case studies play a significant role in knowledge development across various disciplines. Analysis of cases provides an avenue for researchers to explore phenomena within their context based on the collected data.

This can result in the production of rich, practical insights that can be instrumental in both theory-building and practice. Case studies allow researchers to delve into the intricacies and complexities of real-life situations, uncovering insights that might otherwise remain hidden.

Types of case studies

In qualitative research , a case study is not a one-size-fits-all approach. Depending on the nature of the research question and the specific objectives of the study, researchers might choose to use different types of case studies. These types differ in their focus, methodology, and the level of detail they provide about the phenomenon under investigation.

Understanding these types is crucial for selecting the most appropriate approach for your research project and effectively achieving your research goals. Let's briefly look at the main types of case studies.

Exploratory case studies

Exploratory case studies are typically conducted to develop a theory or framework around an understudied phenomenon. They can also serve as a precursor to a larger-scale research project. Exploratory case studies are useful when a researcher wants to identify the key issues or questions which can spur more extensive study or be used to develop propositions for further research. These case studies are characterized by flexibility, allowing researchers to explore various aspects of a phenomenon as they emerge, which can also form the foundation for subsequent studies.

Descriptive case studies

Descriptive case studies aim to provide a complete and accurate representation of a phenomenon or event within its context. These case studies are often based on an established theoretical framework, which guides how data is collected and analyzed. The researcher is concerned with describing the phenomenon in detail, as it occurs naturally, without trying to influence or manipulate it.

Explanatory case studies

Explanatory case studies are focused on explanation - they seek to clarify how or why certain phenomena occur. Often used in complex, real-life situations, they can be particularly valuable in clarifying causal relationships among concepts and understanding the interplay between different factors within a specific context.

Intrinsic, instrumental, and collective case studies

These three categories of case studies focus on the nature and purpose of the study. An intrinsic case study is conducted when a researcher has an inherent interest in the case itself. Instrumental case studies are employed when the case is used to provide insight into a particular issue or phenomenon. A collective case study, on the other hand, involves studying multiple cases simultaneously to investigate some general phenomena.

Each type of case study serves a different purpose and has its own strengths and challenges. The selection of the type should be guided by the research question and objectives, as well as the context and constraints of the research.

The flexibility, depth, and contextual richness offered by case studies make this approach an excellent research method for various fields of study. They enable researchers to investigate real-world phenomena within their specific contexts, capturing nuances that other research methods might miss. Across numerous fields, case studies provide valuable insights into complex issues.

Critical information systems research

Case studies provide a detailed understanding of the role and impact of information systems in different contexts. They offer a platform to explore how information systems are designed, implemented, and used and how they interact with various social, economic, and political factors. Case studies in this field often focus on examining the intricate relationship between technology, organizational processes, and user behavior, helping to uncover insights that can inform better system design and implementation.

Health research

Health research is another field where case studies are highly valuable. They offer a way to explore patient experiences, healthcare delivery processes, and the impact of various interventions in a real-world context.

Case studies can provide a deep understanding of a patient's journey, giving insights into the intricacies of disease progression, treatment effects, and the psychosocial aspects of health and illness.

Asthma research studies

Specifically within medical research, studies on asthma often employ case studies to explore the individual and environmental factors that influence asthma development, management, and outcomes. A case study can provide rich, detailed data about individual patients' experiences, from the triggers and symptoms they experience to the effectiveness of various management strategies. This can be crucial for developing patient-centered asthma care approaches.

Other fields

Apart from the fields mentioned, case studies are also extensively used in business and management research, education research, and political sciences, among many others. They provide an opportunity to delve into the intricacies of real-world situations, allowing for a comprehensive understanding of various phenomena.

Case studies, with their depth and contextual focus, offer unique insights across these varied fields. They allow researchers to illuminate the complexities of real-life situations, contributing to both theory and practice.

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Understanding the key elements of case study design is crucial for conducting rigorous and impactful case study research. A well-structured design guides the researcher through the process, ensuring that the study is methodologically sound and its findings are reliable and valid. The main elements of case study design include the research question , propositions, units of analysis, and the logic linking the data to the propositions.

The research question is the foundation of any research study. A good research question guides the direction of the study and informs the selection of the case, the methods of collecting data, and the analysis techniques. A well-formulated research question in case study research is typically clear, focused, and complex enough to merit further detailed examination of the relevant case(s).

Propositions

Propositions, though not necessary in every case study, provide a direction by stating what we might expect to find in the data collected. They guide how data is collected and analyzed by helping researchers focus on specific aspects of the case. They are particularly important in explanatory case studies, which seek to understand the relationships among concepts within the studied phenomenon.

Units of analysis

The unit of analysis refers to the case, or the main entity or entities that are being analyzed in the study. In case study research, the unit of analysis can be an individual, a group, an organization, a decision, an event, or even a time period. It's crucial to clearly define the unit of analysis, as it shapes the qualitative data analysis process by allowing the researcher to analyze a particular case and synthesize analysis across multiple case studies to draw conclusions.

Argumentation

This refers to the inferential model that allows researchers to draw conclusions from the data. The researcher needs to ensure that there is a clear link between the data, the propositions (if any), and the conclusions drawn. This argumentation is what enables the researcher to make valid and credible inferences about the phenomenon under study.

Understanding and carefully considering these elements in the design phase of a case study can significantly enhance the quality of the research. It can help ensure that the study is methodologically sound and its findings contribute meaningful insights about the case.

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Conducting a case study involves several steps, from defining the research question and selecting the case to collecting and analyzing data . This section outlines these key stages, providing a practical guide on how to conduct case study research.

Defining the research question

The first step in case study research is defining a clear, focused research question. This question should guide the entire research process, from case selection to analysis. It's crucial to ensure that the research question is suitable for a case study approach. Typically, such questions are exploratory or descriptive in nature and focus on understanding a phenomenon within its real-life context.

Selecting and defining the case

The selection of the case should be based on the research question and the objectives of the study. It involves choosing a unique example or a set of examples that provide rich, in-depth data about the phenomenon under investigation. After selecting the case, it's crucial to define it clearly, setting the boundaries of the case, including the time period and the specific context.

Previous research can help guide the case study design. When considering a case study, an example of a case could be taken from previous case study research and used to define cases in a new research inquiry. Considering recently published examples can help understand how to select and define cases effectively.

Developing a detailed case study protocol

A case study protocol outlines the procedures and general rules to be followed during the case study. This includes the data collection methods to be used, the sources of data, and the procedures for analysis. Having a detailed case study protocol ensures consistency and reliability in the study.

The protocol should also consider how to work with the people involved in the research context to grant the research team access to collecting data. As mentioned in previous sections of this guide, establishing rapport is an essential component of qualitative research as it shapes the overall potential for collecting and analyzing data.

Collecting data

Gathering data in case study research often involves multiple sources of evidence, including documents, archival records, interviews, observations, and physical artifacts. This allows for a comprehensive understanding of the case. The process for gathering data should be systematic and carefully documented to ensure the reliability and validity of the study.

Analyzing and interpreting data

The next step is analyzing the data. This involves organizing the data , categorizing it into themes or patterns , and interpreting these patterns to answer the research question. The analysis might also involve comparing the findings with prior research or theoretical propositions.

Writing the case study report

The final step is writing the case study report . This should provide a detailed description of the case, the data, the analysis process, and the findings. The report should be clear, organized, and carefully written to ensure that the reader can understand the case and the conclusions drawn from it.

Each of these steps is crucial in ensuring that the case study research is rigorous, reliable, and provides valuable insights about the case.

The type, depth, and quality of data in your study can significantly influence the validity and utility of the study. In case study research, data is usually collected from multiple sources to provide a comprehensive and nuanced understanding of the case. This section will outline the various methods of collecting data used in case study research and discuss considerations for ensuring the quality of the data.

Interviews are a common method of gathering data in case study research. They can provide rich, in-depth data about the perspectives, experiences, and interpretations of the individuals involved in the case. Interviews can be structured , semi-structured , or unstructured , depending on the research question and the degree of flexibility needed.

Observations

Observations involve the researcher observing the case in its natural setting, providing first-hand information about the case and its context. Observations can provide data that might not be revealed in interviews or documents, such as non-verbal cues or contextual information.

Documents and artifacts

Documents and archival records provide a valuable source of data in case study research. They can include reports, letters, memos, meeting minutes, email correspondence, and various public and private documents related to the case.

These records can provide historical context, corroborate evidence from other sources, and offer insights into the case that might not be apparent from interviews or observations.

Physical artifacts refer to any physical evidence related to the case, such as tools, products, or physical environments. These artifacts can provide tangible insights into the case, complementing the data gathered from other sources.

Ensuring the quality of data collection

Determining the quality of data in case study research requires careful planning and execution. It's crucial to ensure that the data is reliable, accurate, and relevant to the research question. This involves selecting appropriate methods of collecting data, properly training interviewers or observers, and systematically recording and storing the data. It also includes considering ethical issues related to collecting and handling data, such as obtaining informed consent and ensuring the privacy and confidentiality of the participants.

Data analysis

Analyzing case study research involves making sense of the rich, detailed data to answer the research question. This process can be challenging due to the volume and complexity of case study data. However, a systematic and rigorous approach to analysis can ensure that the findings are credible and meaningful. This section outlines the main steps and considerations in analyzing data in case study research.

Organizing the data

The first step in the analysis is organizing the data. This involves sorting the data into manageable sections, often according to the data source or the theme. This step can also involve transcribing interviews, digitizing physical artifacts, or organizing observational data.

Categorizing and coding the data

Once the data is organized, the next step is to categorize or code the data. This involves identifying common themes, patterns, or concepts in the data and assigning codes to relevant data segments. Coding can be done manually or with the help of software tools, and in either case, qualitative analysis software can greatly facilitate the entire coding process. Coding helps to reduce the data to a set of themes or categories that can be more easily analyzed.

Identifying patterns and themes

After coding the data, the researcher looks for patterns or themes in the coded data. This involves comparing and contrasting the codes and looking for relationships or patterns among them. The identified patterns and themes should help answer the research question.

Interpreting the data

Once patterns and themes have been identified, the next step is to interpret these findings. This involves explaining what the patterns or themes mean in the context of the research question and the case. This interpretation should be grounded in the data, but it can also involve drawing on theoretical concepts or prior research.

Verification of the data

The last step in the analysis is verification. This involves checking the accuracy and consistency of the analysis process and confirming that the findings are supported by the data. This can involve re-checking the original data, checking the consistency of codes, or seeking feedback from research participants or peers.

Like any research method , case study research has its strengths and limitations. Researchers must be aware of these, as they can influence the design, conduct, and interpretation of the study.

Understanding the strengths and limitations of case study research can also guide researchers in deciding whether this approach is suitable for their research question . This section outlines some of the key strengths and limitations of case study research.

Benefits include the following:

• Rich, detailed data: One of the main strengths of case study research is that it can generate rich, detailed data about the case. This can provide a deep understanding of the case and its context, which can be valuable in exploring complex phenomena.
• Flexibility: Case study research is flexible in terms of design , data collection , and analysis . A sufficient degree of flexibility allows the researcher to adapt the study according to the case and the emerging findings.
• Real-world context: Case study research involves studying the case in its real-world context, which can provide valuable insights into the interplay between the case and its context.
• Multiple sources of evidence: Case study research often involves collecting data from multiple sources , which can enhance the robustness and validity of the findings.

On the other hand, researchers should consider the following limitations:

• Generalizability: A common criticism of case study research is that its findings might not be generalizable to other cases due to the specificity and uniqueness of each case.
• Time and resource intensive: Case study research can be time and resource intensive due to the depth of the investigation and the amount of collected data.
• Complexity of analysis: The rich, detailed data generated in case study research can make analyzing the data challenging.
• Subjectivity: Given the nature of case study research, there may be a higher degree of subjectivity in interpreting the data , so researchers need to reflect on this and transparently convey to audiences how the research was conducted.

Being aware of these strengths and limitations can help researchers design and conduct case study research effectively and interpret and report the findings appropriately.

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• Knowledge Base
• Methodology
• Case Study | Definition, Examples & Methods

Case Study | Definition, Examples & Methods

Published on 5 May 2022 by Shona McCombes . Revised on 30 January 2023.

A case study is a detailed study of a specific subject, such as a person, group, place, event, organisation, or phenomenon. Case studies are commonly used in social, educational, clinical, and business research.

A case study research design usually involves qualitative methods , but quantitative methods are sometimes also used. Case studies are good for describing , comparing, evaluating, and understanding different aspects of a research problem .

Table of contents

When to do a case study, step 1: select a case, step 2: build a theoretical framework, step 3: collect your data, step 4: describe and analyse the case.

A case study is an appropriate research design when you want to gain concrete, contextual, in-depth knowledge about a specific real-world subject. It allows you to explore the key characteristics, meanings, and implications of the case.

Case studies are often a good choice in a thesis or dissertation . They keep your project focused and manageable when you don’t have the time or resources to do large-scale research.

You might use just one complex case study where you explore a single subject in depth, or conduct multiple case studies to compare and illuminate different aspects of your research problem.

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Once you have developed your problem statement and research questions , you should be ready to choose the specific case that you want to focus on. A good case study should have the potential to:

• Provide new or unexpected insights into the subject
• Challenge or complicate existing assumptions and theories
• Propose practical courses of action to resolve a problem
• Open up new directions for future research

Unlike quantitative or experimental research, a strong case study does not require a random or representative sample. In fact, case studies often deliberately focus on unusual, neglected, or outlying cases which may shed new light on the research problem.

If you find yourself aiming to simultaneously investigate and solve an issue, consider conducting action research . As its name suggests, action research conducts research and takes action at the same time, and is highly iterative and flexible. 

However, you can also choose a more common or representative case to exemplify a particular category, experience, or phenomenon.

While case studies focus more on concrete details than general theories, they should usually have some connection with theory in the field. This way the case study is not just an isolated description, but is integrated into existing knowledge about the topic. It might aim to:

• Exemplify a theory by showing how it explains the case under investigation
• Expand on a theory by uncovering new concepts and ideas that need to be incorporated
• Challenge a theory by exploring an outlier case that doesn’t fit with established assumptions

To ensure that your analysis of the case has a solid academic grounding, you should conduct a literature review of sources related to the topic and develop a theoretical framework . This means identifying key concepts and theories to guide your analysis and interpretation.

There are many different research methods you can use to collect data on your subject. Case studies tend to focus on qualitative data using methods such as interviews, observations, and analysis of primary and secondary sources (e.g., newspaper articles, photographs, official records). Sometimes a case study will also collect quantitative data .

The aim is to gain as thorough an understanding as possible of the case and its context.

In writing up the case study, you need to bring together all the relevant aspects to give as complete a picture as possible of the subject.

How you report your findings depends on the type of research you are doing. Some case studies are structured like a standard scientific paper or thesis, with separate sections or chapters for the methods , results , and discussion .

Others are written in a more narrative style, aiming to explore the case from various angles and analyse its meanings and implications (for example, by using textual analysis or discourse analysis ).

In all cases, though, make sure to give contextual details about the case, connect it back to the literature and theory, and discuss how it fits into wider patterns or debates.

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Meaning of case study in English

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case study | American Dictionary

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Definition of case study

Examples of case study in a sentence.

These examples are programmatically compiled from various online sources to illustrate current usage of the word 'case study.' Any opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback about these examples.

Word History

1914, in the meaning defined at sense 1

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“Case study.” Merriam-Webster.com Dictionary , Merriam-Webster, https://www.merriam-webster.com/dictionary/case%20study. Accessed 6 Jun. 2024.

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What Is a Case Study?

Weighing the pros and cons of this method of research

Kendra Cherry, MS, is a psychosocial rehabilitation specialist, psychology educator, and author of the "Everything Psychology Book."

Cara Lustik is a fact-checker and copywriter.

Verywell / Colleen Tighe

• Pros and Cons

What Types of Case Studies Are Out There?

Where do you find data for a case study, how do i write a psychology case study.

A case study is an in-depth study of one person, group, or event. In a case study, nearly every aspect of the subject's life and history is analyzed to seek patterns and causes of behavior. Case studies can be used in many different fields, including psychology, medicine, education, anthropology, political science, and social work.

The point of a case study is to learn as much as possible about an individual or group so that the information can be generalized to many others. Unfortunately, case studies tend to be highly subjective, and it is sometimes difficult to generalize results to a larger population.

While case studies focus on a single individual or group, they follow a format similar to other types of psychology writing. If you are writing a case study, we got you—here are some rules of APA format to reference.  

At a Glance

A case study, or an in-depth study of a person, group, or event, can be a useful research tool when used wisely. In many cases, case studies are best used in situations where it would be difficult or impossible for you to conduct an experiment. They are helpful for looking at unique situations and allow researchers to gather a lot of˜ information about a specific individual or group of people. However, it's important to be cautious of any bias we draw from them as they are highly subjective.

What Are the Benefits and Limitations of Case Studies?

A case study can have its strengths and weaknesses. Researchers must consider these pros and cons before deciding if this type of study is appropriate for their needs.

One of the greatest advantages of a case study is that it allows researchers to investigate things that are often difficult or impossible to replicate in a lab. Some other benefits of a case study:

• Allows researchers to capture information on the 'how,' 'what,' and 'why,' of something that's implemented
• Gives researchers the chance to collect information on why one strategy might be chosen over another
• Permits researchers to develop hypotheses that can be explored in experimental research

On the other hand, a case study can have some drawbacks:

• It cannot necessarily be generalized to the larger population
• Cannot demonstrate cause and effect
• It may not be scientifically rigorous
• It can lead to bias

Researchers may choose to perform a case study if they want to explore a unique or recently discovered phenomenon. Through their insights, researchers develop additional ideas and study questions that might be explored in future studies.

It's important to remember that the insights from case studies cannot be used to determine cause-and-effect relationships between variables. However, case studies may be used to develop hypotheses that can then be addressed in experimental research.

Case Study Examples

There have been a number of notable case studies in the history of psychology. Much of  Freud's work and theories were developed through individual case studies. Some great examples of case studies in psychology include:

• Anna O : Anna O. was a pseudonym of a woman named Bertha Pappenheim, a patient of a physician named Josef Breuer. While she was never a patient of Freud's, Freud and Breuer discussed her case extensively. The woman was experiencing symptoms of a condition that was then known as hysteria and found that talking about her problems helped relieve her symptoms. Her case played an important part in the development of talk therapy as an approach to mental health treatment.
• Phineas Gage : Phineas Gage was a railroad employee who experienced a terrible accident in which an explosion sent a metal rod through his skull, damaging important portions of his brain. Gage recovered from his accident but was left with serious changes in both personality and behavior.
• Genie : Genie was a young girl subjected to horrific abuse and isolation. The case study of Genie allowed researchers to study whether language learning was possible, even after missing critical periods for language development. Her case also served as an example of how scientific research may interfere with treatment and lead to further abuse of vulnerable individuals.

Such cases demonstrate how case research can be used to study things that researchers could not replicate in experimental settings. In Genie's case, her horrific abuse denied her the opportunity to learn a language at critical points in her development.

This is clearly not something researchers could ethically replicate, but conducting a case study on Genie allowed researchers to study phenomena that are otherwise impossible to reproduce.

There are a few different types of case studies that psychologists and other researchers might use:

• Collective case studies : These involve studying a group of individuals. Researchers might study a group of people in a certain setting or look at an entire community. For example, psychologists might explore how access to resources in a community has affected the collective mental well-being of those who live there.
• Descriptive case studies : These involve starting with a descriptive theory. The subjects are then observed, and the information gathered is compared to the pre-existing theory.
• Explanatory case studies : These   are often used to do causal investigations. In other words, researchers are interested in looking at factors that may have caused certain things to occur.
• Exploratory case studies : These are sometimes used as a prelude to further, more in-depth research. This allows researchers to gather more information before developing their research questions and hypotheses .
• Instrumental case studies : These occur when the individual or group allows researchers to understand more than what is initially obvious to observers.
• Intrinsic case studies : This type of case study is when the researcher has a personal interest in the case. Jean Piaget's observations of his own children are good examples of how an intrinsic case study can contribute to the development of a psychological theory.

The three main case study types often used are intrinsic, instrumental, and collective. Intrinsic case studies are useful for learning about unique cases. Instrumental case studies help look at an individual to learn more about a broader issue. A collective case study can be useful for looking at several cases simultaneously.

The type of case study that psychology researchers use depends on the unique characteristics of the situation and the case itself.

There are a number of different sources and methods that researchers can use to gather information about an individual or group. Six major sources that have been identified by researchers are:

• Archival records : Census records, survey records, and name lists are examples of archival records.
• Direct observation : This strategy involves observing the subject, often in a natural setting . While an individual observer is sometimes used, it is more common to utilize a group of observers.
• Documents : Letters, newspaper articles, administrative records, etc., are the types of documents often used as sources.
• Interviews : Interviews are one of the most important methods for gathering information in case studies. An interview can involve structured survey questions or more open-ended questions.
• Participant observation : When the researcher serves as a participant in events and observes the actions and outcomes, it is called participant observation.
• Physical artifacts : Tools, objects, instruments, and other artifacts are often observed during a direct observation of the subject.

If you have been directed to write a case study for a psychology course, be sure to check with your instructor for any specific guidelines you need to follow. If you are writing your case study for a professional publication, check with the publisher for their specific guidelines for submitting a case study.

Here is a general outline of what should be included in a case study.

Section 1: A Case History

This section will have the following structure and content:

Background information : The first section of your paper will present your client's background. Include factors such as age, gender, work, health status, family mental health history, family and social relationships, drug and alcohol history, life difficulties, goals, and coping skills and weaknesses.

Description of the presenting problem : In the next section of your case study, you will describe the problem or symptoms that the client presented with.

Describe any physical, emotional, or sensory symptoms reported by the client. Thoughts, feelings, and perceptions related to the symptoms should also be noted. Any screening or diagnostic assessments that are used should also be described in detail and all scores reported.

Your diagnosis : Provide your diagnosis and give the appropriate Diagnostic and Statistical Manual code. Explain how you reached your diagnosis, how the client's symptoms fit the diagnostic criteria for the disorder(s), or any possible difficulties in reaching a diagnosis.

Section 2: Treatment Plan

This portion of the paper will address the chosen treatment for the condition. This might also include the theoretical basis for the chosen treatment or any other evidence that might exist to support why this approach was chosen.

• Cognitive behavioral approach : Explain how a cognitive behavioral therapist would approach treatment. Offer background information on cognitive behavioral therapy and describe the treatment sessions, client response, and outcome of this type of treatment. Make note of any difficulties or successes encountered by your client during treatment.
• Humanistic approach : Describe a humanistic approach that could be used to treat your client, such as client-centered therapy . Provide information on the type of treatment you chose, the client's reaction to the treatment, and the end result of this approach. Explain why the treatment was successful or unsuccessful.
• Psychoanalytic approach : Describe how a psychoanalytic therapist would view the client's problem. Provide some background on the psychoanalytic approach and cite relevant references. Explain how psychoanalytic therapy would be used to treat the client, how the client would respond to therapy, and the effectiveness of this treatment approach.
• Pharmacological approach : If treatment primarily involves the use of medications, explain which medications were used and why. Provide background on the effectiveness of these medications and how monotherapy may compare with an approach that combines medications with therapy or other treatments.

This section of a case study should also include information about the treatment goals, process, and outcomes.

When you are writing a case study, you should also include a section where you discuss the case study itself, including the strengths and limitiations of the study. You should note how the findings of your case study might support previous research. 

In your discussion section, you should also describe some of the implications of your case study. What ideas or findings might require further exploration? How might researchers go about exploring some of these questions in additional studies?

Need More Tips?

Here are a few additional pointers to keep in mind when formatting your case study:

• Never refer to the subject of your case study as "the client." Instead, use their name or a pseudonym.
• Read examples of case studies to gain an idea about the style and format.
• Remember to use APA format when citing references .

Crowe S, Cresswell K, Robertson A, Huby G, Avery A, Sheikh A. The case study approach .  BMC Med Res Methodol . 2011;11:100.

Crowe S, Cresswell K, Robertson A, Huby G, Avery A, Sheikh A. The case study approach . BMC Med Res Methodol . 2011 Jun 27;11:100. doi:10.1186/1471-2288-11-100

Gagnon, Yves-Chantal.  The Case Study as Research Method: A Practical Handbook . Canada, Chicago Review Press Incorporated DBA Independent Pub Group, 2010.

Yin, Robert K. Case Study Research and Applications: Design and Methods . United States, SAGE Publications, 2017.

By Kendra Cherry, MSEd Kendra Cherry, MS, is a psychosocial rehabilitation specialist, psychology educator, and author of the "Everything Psychology Book."

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Case Study – Methods, Examples and Guide

Table of Contents

A case study is a research method that involves an in-depth examination and analysis of a particular phenomenon or case, such as an individual, organization, community, event, or situation.

It is a qualitative research approach that aims to provide a detailed and comprehensive understanding of the case being studied. Case studies typically involve multiple sources of data, including interviews, observations, documents, and artifacts, which are analyzed using various techniques, such as content analysis, thematic analysis, and grounded theory. The findings of a case study are often used to develop theories, inform policy or practice, or generate new research questions.

Types of Case Study

Types and Methods of Case Study are as follows:

Single-Case Study

A single-case study is an in-depth analysis of a single case. This type of case study is useful when the researcher wants to understand a specific phenomenon in detail.

For Example , A researcher might conduct a single-case study on a particular individual to understand their experiences with a particular health condition or a specific organization to explore their management practices. The researcher collects data from multiple sources, such as interviews, observations, and documents, and uses various techniques to analyze the data, such as content analysis or thematic analysis. The findings of a single-case study are often used to generate new research questions, develop theories, or inform policy or practice.

Multiple-Case Study

A multiple-case study involves the analysis of several cases that are similar in nature. This type of case study is useful when the researcher wants to identify similarities and differences between the cases.

For Example, a researcher might conduct a multiple-case study on several companies to explore the factors that contribute to their success or failure. The researcher collects data from each case, compares and contrasts the findings, and uses various techniques to analyze the data, such as comparative analysis or pattern-matching. The findings of a multiple-case study can be used to develop theories, inform policy or practice, or generate new research questions.

Exploratory Case Study

An exploratory case study is used to explore a new or understudied phenomenon. This type of case study is useful when the researcher wants to generate hypotheses or theories about the phenomenon.

For Example, a researcher might conduct an exploratory case study on a new technology to understand its potential impact on society. The researcher collects data from multiple sources, such as interviews, observations, and documents, and uses various techniques to analyze the data, such as grounded theory or content analysis. The findings of an exploratory case study can be used to generate new research questions, develop theories, or inform policy or practice.

Descriptive Case Study

A descriptive case study is used to describe a particular phenomenon in detail. This type of case study is useful when the researcher wants to provide a comprehensive account of the phenomenon.

For Example, a researcher might conduct a descriptive case study on a particular community to understand its social and economic characteristics. The researcher collects data from multiple sources, such as interviews, observations, and documents, and uses various techniques to analyze the data, such as content analysis or thematic analysis. The findings of a descriptive case study can be used to inform policy or practice or generate new research questions.

Instrumental Case Study

An instrumental case study is used to understand a particular phenomenon that is instrumental in achieving a particular goal. This type of case study is useful when the researcher wants to understand the role of the phenomenon in achieving the goal.

For Example, a researcher might conduct an instrumental case study on a particular policy to understand its impact on achieving a particular goal, such as reducing poverty. The researcher collects data from multiple sources, such as interviews, observations, and documents, and uses various techniques to analyze the data, such as content analysis or thematic analysis. The findings of an instrumental case study can be used to inform policy or practice or generate new research questions.

Case Study Data Collection Methods

Here are some common data collection methods for case studies:

Interviews involve asking questions to individuals who have knowledge or experience relevant to the case study. Interviews can be structured (where the same questions are asked to all participants) or unstructured (where the interviewer follows up on the responses with further questions). Interviews can be conducted in person, over the phone, or through video conferencing.

Observations

Observations involve watching and recording the behavior and activities of individuals or groups relevant to the case study. Observations can be participant (where the researcher actively participates in the activities) or non-participant (where the researcher observes from a distance). Observations can be recorded using notes, audio or video recordings, or photographs.

Documents can be used as a source of information for case studies. Documents can include reports, memos, emails, letters, and other written materials related to the case study. Documents can be collected from the case study participants or from public sources.

Surveys involve asking a set of questions to a sample of individuals relevant to the case study. Surveys can be administered in person, over the phone, through mail or email, or online. Surveys can be used to gather information on attitudes, opinions, or behaviors related to the case study.

Artifacts are physical objects relevant to the case study. Artifacts can include tools, equipment, products, or other objects that provide insights into the case study phenomenon.

How to conduct Case Study Research

Conducting a case study research involves several steps that need to be followed to ensure the quality and rigor of the study. Here are the steps to conduct case study research:

• Define the research questions: The first step in conducting a case study research is to define the research questions. The research questions should be specific, measurable, and relevant to the case study phenomenon under investigation.
• Select the case: The next step is to select the case or cases to be studied. The case should be relevant to the research questions and should provide rich and diverse data that can be used to answer the research questions.
• Collect data: Data can be collected using various methods, such as interviews, observations, documents, surveys, and artifacts. The data collection method should be selected based on the research questions and the nature of the case study phenomenon.
• Analyze the data: The data collected from the case study should be analyzed using various techniques, such as content analysis, thematic analysis, or grounded theory. The analysis should be guided by the research questions and should aim to provide insights and conclusions relevant to the research questions.
• Draw conclusions: The conclusions drawn from the case study should be based on the data analysis and should be relevant to the research questions. The conclusions should be supported by evidence and should be clearly stated.
• Validate the findings: The findings of the case study should be validated by reviewing the data and the analysis with participants or other experts in the field. This helps to ensure the validity and reliability of the findings.
• Write the report: The final step is to write the report of the case study research. The report should provide a clear description of the case study phenomenon, the research questions, the data collection methods, the data analysis, the findings, and the conclusions. The report should be written in a clear and concise manner and should follow the guidelines for academic writing.

Examples of Case Study

Here are some examples of case study research:

• The Hawthorne Studies : Conducted between 1924 and 1932, the Hawthorne Studies were a series of case studies conducted by Elton Mayo and his colleagues to examine the impact of work environment on employee productivity. The studies were conducted at the Hawthorne Works plant of the Western Electric Company in Chicago and included interviews, observations, and experiments.
• The Stanford Prison Experiment: Conducted in 1971, the Stanford Prison Experiment was a case study conducted by Philip Zimbardo to examine the psychological effects of power and authority. The study involved simulating a prison environment and assigning participants to the role of guards or prisoners. The study was controversial due to the ethical issues it raised.
• The Challenger Disaster: The Challenger Disaster was a case study conducted to examine the causes of the Space Shuttle Challenger explosion in 1986. The study included interviews, observations, and analysis of data to identify the technical, organizational, and cultural factors that contributed to the disaster.
• The Enron Scandal: The Enron Scandal was a case study conducted to examine the causes of the Enron Corporation’s bankruptcy in 2001. The study included interviews, analysis of financial data, and review of documents to identify the accounting practices, corporate culture, and ethical issues that led to the company’s downfall.
• The Fukushima Nuclear Disaster : The Fukushima Nuclear Disaster was a case study conducted to examine the causes of the nuclear accident that occurred at the Fukushima Daiichi Nuclear Power Plant in Japan in 2011. The study included interviews, analysis of data, and review of documents to identify the technical, organizational, and cultural factors that contributed to the disaster.

Application of Case Study

Case studies have a wide range of applications across various fields and industries. Here are some examples:

Business and Management

Case studies are widely used in business and management to examine real-life situations and develop problem-solving skills. Case studies can help students and professionals to develop a deep understanding of business concepts, theories, and best practices.

Case studies are used in healthcare to examine patient care, treatment options, and outcomes. Case studies can help healthcare professionals to develop critical thinking skills, diagnose complex medical conditions, and develop effective treatment plans.

Case studies are used in education to examine teaching and learning practices. Case studies can help educators to develop effective teaching strategies, evaluate student progress, and identify areas for improvement.

Social Sciences

Case studies are widely used in social sciences to examine human behavior, social phenomena, and cultural practices. Case studies can help researchers to develop theories, test hypotheses, and gain insights into complex social issues.

Law and Ethics

Case studies are used in law and ethics to examine legal and ethical dilemmas. Case studies can help lawyers, policymakers, and ethical professionals to develop critical thinking skills, analyze complex cases, and make informed decisions.

Purpose of Case Study

The purpose of a case study is to provide a detailed analysis of a specific phenomenon, issue, or problem in its real-life context. A case study is a qualitative research method that involves the in-depth exploration and analysis of a particular case, which can be an individual, group, organization, event, or community.

The primary purpose of a case study is to generate a comprehensive and nuanced understanding of the case, including its history, context, and dynamics. Case studies can help researchers to identify and examine the underlying factors, processes, and mechanisms that contribute to the case and its outcomes. This can help to develop a more accurate and detailed understanding of the case, which can inform future research, practice, or policy.

Case studies can also serve other purposes, including:

• Illustrating a theory or concept: Case studies can be used to illustrate and explain theoretical concepts and frameworks, providing concrete examples of how they can be applied in real-life situations.
• Developing hypotheses: Case studies can help to generate hypotheses about the causal relationships between different factors and outcomes, which can be tested through further research.
• Providing insight into complex issues: Case studies can provide insights into complex and multifaceted issues, which may be difficult to understand through other research methods.
• Informing practice or policy: Case studies can be used to inform practice or policy by identifying best practices, lessons learned, or areas for improvement.

Advantages of Case Study Research

There are several advantages of case study research, including:

• In-depth exploration: Case study research allows for a detailed exploration and analysis of a specific phenomenon, issue, or problem in its real-life context. This can provide a comprehensive understanding of the case and its dynamics, which may not be possible through other research methods.
• Rich data: Case study research can generate rich and detailed data, including qualitative data such as interviews, observations, and documents. This can provide a nuanced understanding of the case and its complexity.
• Holistic perspective: Case study research allows for a holistic perspective of the case, taking into account the various factors, processes, and mechanisms that contribute to the case and its outcomes. This can help to develop a more accurate and comprehensive understanding of the case.
• Theory development: Case study research can help to develop and refine theories and concepts by providing empirical evidence and concrete examples of how they can be applied in real-life situations.
• Practical application: Case study research can inform practice or policy by identifying best practices, lessons learned, or areas for improvement.
• Contextualization: Case study research takes into account the specific context in which the case is situated, which can help to understand how the case is influenced by the social, cultural, and historical factors of its environment.

Limitations of Case Study Research

There are several limitations of case study research, including:

• Limited generalizability : Case studies are typically focused on a single case or a small number of cases, which limits the generalizability of the findings. The unique characteristics of the case may not be applicable to other contexts or populations, which may limit the external validity of the research.
• Biased sampling: Case studies may rely on purposive or convenience sampling, which can introduce bias into the sample selection process. This may limit the representativeness of the sample and the generalizability of the findings.
• Subjectivity: Case studies rely on the interpretation of the researcher, which can introduce subjectivity into the analysis. The researcher’s own biases, assumptions, and perspectives may influence the findings, which may limit the objectivity of the research.
• Limited control: Case studies are typically conducted in naturalistic settings, which limits the control that the researcher has over the environment and the variables being studied. This may limit the ability to establish causal relationships between variables.
• Time-consuming: Case studies can be time-consuming to conduct, as they typically involve a detailed exploration and analysis of a specific case. This may limit the feasibility of conducting multiple case studies or conducting case studies in a timely manner.
• Resource-intensive: Case studies may require significant resources, including time, funding, and expertise. This may limit the ability of researchers to conduct case studies in resource-constrained settings.

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Researcher, Academic Writer, Web developer

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Writing a Case Study

What is a case study?

A Case study is: 

• An in-depth research design that primarily uses a qualitative methodology but sometimes​​ includes quantitative methodology.
• Used to examine an identifiable problem confirmed through research.
• Used to investigate an individual, group of people, organization, or event.
• Used to mostly answer "how" and "why" questions.

What are the different types of case studies?

Note: These are the primary case studies. As you continue to research and learn

about case studies you will begin to find a robust list of different types. 

Who are your case study participants?

What is triangulation ? 

Validity and credibility are an essential part of the case study. Therefore, the researcher should include triangulation to ensure trustworthiness while accurately reflecting what the researcher seeks to investigate.

How to write a Case Study?

When developing a case study, there are different ways you could present the information, but remember to include the five parts for your case study.

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• Writing a Case Study
• About Informed Consent
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• Acknowledgments

A case study research paper examines a person, place, event, condition, phenomenon, or other type of subject of analysis in order to extrapolate  key themes and results that help predict future trends, illuminate previously hidden issues that can be applied to practice, and/or provide a means for understanding an important research problem with greater clarity. A case study research paper usually examines a single subject of analysis, but case study papers can also be designed as a comparative investigation that shows relationships between two or more subjects. The methods used to study a case can rest within a quantitative, qualitative, or mixed-method investigative paradigm.

Case Studies. Writing@CSU. Colorado State University; Mills, Albert J. , Gabrielle Durepos, and Eiden Wiebe, editors. Encyclopedia of Case Study Research . Thousand Oaks, CA: SAGE Publications, 2010 ; “What is a Case Study?” In Swanborn, Peter G. Case Study Research: What, Why and How? London: SAGE, 2010.

How to Approach Writing a Case Study Research Paper

General information about how to choose a topic to investigate can be found under the " Choosing a Research Problem " tab in the Organizing Your Social Sciences Research Paper writing guide. Review this page because it may help you identify a subject of analysis that can be investigated using a case study design.

However, identifying a case to investigate involves more than choosing the research problem . A case study encompasses a problem contextualized around the application of in-depth analysis, interpretation, and discussion, often resulting in specific recommendations for action or for improving existing conditions. As Seawright and Gerring note, practical considerations such as time and access to information can influence case selection, but these issues should not be the sole factors used in describing the methodological justification for identifying a particular case to study. Given this, selecting a case includes considering the following:

• The case represents an unusual or atypical example of a research problem that requires more in-depth analysis? Cases often represent a topic that rests on the fringes of prior investigations because the case may provide new ways of understanding the research problem. For example, if the research problem is to identify strategies to improve policies that support girl's access to secondary education in predominantly Muslim nations, you could consider using Azerbaijan as a case study rather than selecting a more obvious nation in the Middle East. Doing so may reveal important new insights into recommending how governments in other predominantly Muslim nations can formulate policies that support improved access to education for girls.
• The case provides important insight or illuminate a previously hidden problem? In-depth analysis of a case can be based on the hypothesis that the case study will reveal trends or issues that have not been exposed in prior research or will reveal new and important implications for practice. For example, anecdotal evidence may suggest drug use among homeless veterans is related to their patterns of travel throughout the day. Assuming prior studies have not looked at individual travel choices as a way to study access to illicit drug use, a case study that observes a homeless veteran could reveal how issues of personal mobility choices facilitate regular access to illicit drugs. Note that it is important to conduct a thorough literature review to ensure that your assumption about the need to reveal new insights or previously hidden problems is valid and evidence-based.
• The case challenges and offers a counter-point to prevailing assumptions? Over time, research on any given topic can fall into a trap of developing assumptions based on outdated studies that are still applied to new or changing conditions or the idea that something should simply be accepted as "common sense," even though the issue has not been thoroughly tested in current practice. A case study analysis may offer an opportunity to gather evidence that challenges prevailing assumptions about a research problem and provide a new set of recommendations applied to practice that have not been tested previously. For example, perhaps there has been a long practice among scholars to apply a particular theory in explaining the relationship between two subjects of analysis. Your case could challenge this assumption by applying an innovative theoretical framework [perhaps borrowed from another discipline] to explore whether this approach offers new ways of understanding the research problem. Taking a contrarian stance is one of the most important ways that new knowledge and understanding develops from existing literature.
• The case provides an opportunity to pursue action leading to the resolution of a problem? Another way to think about choosing a case to study is to consider how the results from investigating a particular case may result in findings that reveal ways in which to resolve an existing or emerging problem. For example, studying the case of an unforeseen incident, such as a fatal accident at a railroad crossing, can reveal hidden issues that could be applied to preventative measures that contribute to reducing the chance of accidents in the future. In this example, a case study investigating the accident could lead to a better understanding of where to strategically locate additional signals at other railroad crossings so as to better warn drivers of an approaching train, particularly when visibility is hindered by heavy rain, fog, or at night.
• The case offers a new direction in future research? A case study can be used as a tool for an exploratory investigation that highlights the need for further research about the problem. A case can be used when there are few studies that help predict an outcome or that establish a clear understanding about how best to proceed in addressing a problem. For example, after conducting a thorough literature review [very important!], you discover that little research exists showing the ways in which women contribute to promoting water conservation in rural communities of east central Africa. A case study of how women contribute to saving water in a rural village of Uganda can lay the foundation for understanding the need for more thorough research that documents how women in their roles as cooks and family caregivers think about water as a valuable resource within their community. This example of a case study could also point to the need for scholars to build new theoretical frameworks around the topic [e.g., applying feminist theories of work and family to the issue of water conservation].

Eisenhardt, Kathleen M. “Building Theories from Case Study Research.” Academy of Management Review 14 (October 1989): 532-550; Emmel, Nick. Sampling and Choosing Cases in Qualitative Research: A Realist Approach . Thousand Oaks, CA: SAGE Publications, 2013; Gerring, John. “What Is a Case Study and What Is It Good for?” American Political Science Review 98 (May 2004): 341-354; Mills, Albert J. , Gabrielle Durepos, and Eiden Wiebe, editors. Encyclopedia of Case Study Research . Thousand Oaks, CA: SAGE Publications, 2010; Seawright, Jason and John Gerring. "Case Selection Techniques in Case Study Research." Political Research Quarterly 61 (June 2008): 294-308.

Structure and Writing Style

The purpose of a paper in the social sciences designed around a case study is to thoroughly investigate a subject of analysis in order to reveal a new understanding about the research problem and, in so doing, contributing new knowledge to what is already known from previous studies. In applied social sciences disciplines [e.g., education, social work, public administration, etc.], case studies may also be used to reveal best practices, highlight key programs, or investigate interesting aspects of professional work.

In general, the structure of a case study research paper is not all that different from a standard college-level research paper. However, there are subtle differences you should be aware of. Here are the key elements to organizing and writing a case study research paper.

I.  Introduction

As with any research paper, your introduction should serve as a roadmap for your readers to ascertain the scope and purpose of your study . The introduction to a case study research paper, however, should not only describe the research problem and its significance, but you should also succinctly describe why the case is being used and how it relates to addressing the problem. The two elements should be linked. With this in mind, a good introduction answers these four questions:

• What is being studied? Describe the research problem and describe the subject of analysis [the case] you have chosen to address the problem. Explain how they are linked and what elements of the case will help to expand knowledge and understanding about the problem.
• Why is this topic important to investigate? Describe the significance of the research problem and state why a case study design and the subject of analysis that the paper is designed around is appropriate in addressing the problem.
• What did we know about this topic before I did this study? Provide background that helps lead the reader into the more in-depth literature review to follow. If applicable, summarize prior case study research applied to the research problem and why it fails to adequately address the problem. Describe why your case will be useful. If no prior case studies have been used to address the research problem, explain why you have selected this subject of analysis.
• How will this study advance new knowledge or new ways of understanding? Explain why your case study will be suitable in helping to expand knowledge and understanding about the research problem.

Each of these questions should be addressed in no more than a few paragraphs. Exceptions to this can be when you are addressing a complex research problem or subject of analysis that requires more in-depth background information.

II.  Literature Review

The literature review for a case study research paper is generally structured the same as it is for any college-level research paper. The difference, however, is that the literature review is focused on providing background information and  enabling historical interpretation of the subject of analysis in relation to the research problem the case is intended to address . This includes synthesizing studies that help to:

• Place relevant works in the context of their contribution to understanding the case study being investigated . This would involve summarizing studies that have used a similar subject of analysis to investigate the research problem. If there is literature using the same or a very similar case to study, you need to explain why duplicating past research is important [e.g., conditions have changed; prior studies were conducted long ago, etc.].
• Describe the relationship each work has to the others under consideration that informs the reader why this case is applicable . Your literature review should include a description of any works that support using the case to investigate the research problem and the underlying research questions.
• Identify new ways to interpret prior research using the case study . If applicable, review any research that has examined the research problem using a different research design. Explain how your use of a case study design may reveal new knowledge or a new perspective or that can redirect research in an important new direction.
• Resolve conflicts amongst seemingly contradictory previous studies . This refers to synthesizing any literature that points to unresolved issues of concern about the research problem and describing how the subject of analysis that forms the case study can help resolve these existing contradictions.
• Point the way in fulfilling a need for additional research . Your review should examine any literature that lays a foundation for understanding why your case study design and the subject of analysis around which you have designed your study may reveal a new way of approaching the research problem or offer a perspective that points to the need for additional research.
• Expose any gaps that exist in the literature that the case study could help to fill . Summarize any literature that not only shows how your subject of analysis contributes to understanding the research problem, but how your case contributes to a new way of understanding the problem that prior research has failed to do.
• Locate your own research within the context of existing literature [very important!] . Collectively, your literature review should always place your case study within the larger domain of prior research about the problem. The overarching purpose of reviewing pertinent literature in a case study paper is to demonstrate that you have thoroughly identified and synthesized prior studies in relation to explaining the relevance of the case in addressing the research problem.

III.  Method

In this section, you explain why you selected a particular case [i.e., subject of analysis] and the strategy you used to identify and ultimately decide that your case was appropriate in addressing the research problem. The way you describe the methods used varies depending on the type of subject of analysis that constitutes your case study.

If your subject of analysis is an incident or event . In the social and behavioral sciences, the event or incident that represents the case to be studied is usually bounded by time and place, with a clear beginning and end and with an identifiable location or position relative to its surroundings. The subject of analysis can be a rare or critical event or it can focus on a typical or regular event. The purpose of studying a rare event is to illuminate new ways of thinking about the broader research problem or to test a hypothesis. Critical incident case studies must describe the method by which you identified the event and explain the process by which you determined the validity of this case to inform broader perspectives about the research problem or to reveal new findings. However, the event does not have to be a rare or uniquely significant to support new thinking about the research problem or to challenge an existing hypothesis. For example, Walo, Bull, and Breen conducted a case study to identify and evaluate the direct and indirect economic benefits and costs of a local sports event in the City of Lismore, New South Wales, Australia. The purpose of their study was to provide new insights from measuring the impact of a typical local sports event that prior studies could not measure well because they focused on large "mega-events." Whether the event is rare or not, the methods section should include an explanation of the following characteristics of the event: a) when did it take place; b) what were the underlying circumstances leading to the event; and, c) what were the consequences of the event in relation to the research problem.

If your subject of analysis is a person. Explain why you selected this particular individual to be studied and describe what experiences they have had that provide an opportunity to advance new understandings about the research problem. Mention any background about this person which might help the reader understand the significance of their experiences that make them worthy of study. This includes describing the relationships this person has had with other people, institutions, and/or events that support using them as the subject for a case study research paper. It is particularly important to differentiate the person as the subject of analysis from others and to succinctly explain how the person relates to examining the research problem [e.g., why is one politician in a particular local election used to show an increase in voter turnout from any other candidate running in the election]. Note that these issues apply to a specific group of people used as a case study unit of analysis [e.g., a classroom of students].

If your subject of analysis is a place. In general, a case study that investigates a place suggests a subject of analysis that is unique or special in some way and that this uniqueness can be used to build new understanding or knowledge about the research problem. A case study of a place must not only describe its various attributes relevant to the research problem [e.g., physical, social, historical, cultural, economic, political], but you must state the method by which you determined that this place will illuminate new understandings about the research problem. It is also important to articulate why a particular place as the case for study is being used if similar places also exist [i.e., if you are studying patterns of homeless encampments of veterans in open spaces, explain why you are studying Echo Park in Los Angeles rather than Griffith Park?]. If applicable, describe what type of human activity involving this place makes it a good choice to study [e.g., prior research suggests Echo Park has more homeless veterans].

If your subject of analysis is a phenomenon. A phenomenon refers to a fact, occurrence, or circumstance that can be studied or observed but with the cause or explanation to be in question. In this sense, a phenomenon that forms your subject of analysis can encompass anything that can be observed or presumed to exist but is not fully understood. In the social and behavioral sciences, the case usually focuses on human interaction within a complex physical, social, economic, cultural, or political system. For example, the phenomenon could be the observation that many vehicles used by ISIS fighters are small trucks with English language advertisements on them. The research problem could be that ISIS fighters are difficult to combat because they are highly mobile. The research questions could be how and by what means are these vehicles used by ISIS being supplied to the militants and how might supply lines to these vehicles be cut off? How might knowing the suppliers of these trucks reveal larger networks of collaborators and financial support? A case study of a phenomenon most often encompasses an in-depth analysis of a cause and effect that is grounded in an interactive relationship between people and their environment in some way.

NOTE:   The choice of the case or set of cases to study cannot appear random. Evidence that supports the method by which you identified and chose your subject of analysis should clearly support investigation of the research problem and linked to key findings from your literature review. Be sure to cite any studies that helped you determine that the case you chose was appropriate for examining the problem.

IV.  Discussion

The main elements of your discussion section are generally the same as any research paper, but centered around interpreting and drawing conclusions about the key findings from your analysis of the case study. Note that a general social sciences research paper may contain a separate section to report findings. However, in a paper designed around a case study, it is common to combine a description of the results with the discussion about their implications. The objectives of your discussion section should include the following:

Reiterate the Research Problem/State the Major Findings Briefly reiterate the research problem you are investigating and explain why the subject of analysis around which you designed the case study were used. You should then describe the findings revealed from your study of the case using direct, declarative, and succinct proclamation of the study results. Highlight any findings that were unexpected or especially profound.

Explain the Meaning of the Findings and Why They are Important Systematically explain the meaning of your case study findings and why you believe they are important. Begin this part of the section by repeating what you consider to be your most important or surprising finding first, then systematically review each finding. Be sure to thoroughly extrapolate what your analysis of the case can tell the reader about situations or conditions beyond the actual case that was studied while, at the same time, being careful not to misconstrue or conflate a finding that undermines the external validity of your conclusions.

Relate the Findings to Similar Studies No study in the social sciences is so novel or possesses such a restricted focus that it has absolutely no relation to previously published research. The discussion section should relate your case study results to those found in other studies, particularly if questions raised from prior studies served as the motivation for choosing your subject of analysis. This is important because comparing and contrasting the findings of other studies helps support the overall importance of your results and it highlights how and in what ways your case study design and the subject of analysis differs from prior research about the topic.

Consider Alternative Explanations of the Findings Remember that the purpose of social science research is to discover and not to prove. When writing the discussion section, you should carefully consider all possible explanations revealed by the case study results, rather than just those that fit your hypothesis or prior assumptions and biases. Be alert to what the in-depth analysis of the case may reveal about the research problem, including offering a contrarian perspective to what scholars have stated in prior research if that is how the findings can be interpreted from your case.

Acknowledge the Study's Limitations You can state the study's limitations in the conclusion section of your paper but describing the limitations of your subject of analysis in the discussion section provides an opportunity to identify the limitations and explain why they are not significant. This part of the discussion section should also note any unanswered questions or issues your case study could not address. More detailed information about how to document any limitations to your research can be found here .

Suggest Areas for Further Research Although your case study may offer important insights about the research problem, there are likely additional questions related to the problem that remain unanswered or findings that unexpectedly revealed themselves as a result of your in-depth analysis of the case. Be sure that the recommendations for further research are linked to the research problem and that you explain why your recommendations are valid in other contexts and based on the original assumptions of your study.

V.  Conclusion

As with any research paper, you should summarize your conclusion in clear, simple language; emphasize how the findings from your case study differs from or supports prior research and why. Do not simply reiterate the discussion section. Provide a synthesis of key findings presented in the paper to show how these converge to address the research problem. If you haven't already done so in the discussion section, be sure to document the limitations of your case study and any need for further research.

The function of your paper's conclusion is to: 1) reiterate the main argument supported by the findings from your case study; 2) state clearly the context, background, and necessity of pursuing the research problem using a case study design in relation to an issue, controversy, or a gap found from reviewing the literature; and, 3) provide a place to persuasively and succinctly restate the significance of your research problem, given that the reader has now been presented with in-depth information about the topic.

Consider the following points to help ensure your conclusion is appropriate:

• If the argument or purpose of your paper is complex, you may need to summarize these points for your reader.
• If prior to your conclusion, you have not yet explained the significance of your findings or if you are proceeding inductively, use the conclusion of your paper to describe your main points and explain their significance.
• Move from a detailed to a general level of consideration of the case study's findings that returns the topic to the context provided by the introduction or within a new context that emerges from your case study findings.

Note that, depending on the discipline you are writing in or the preferences of your professor, the concluding paragraph may contain your final reflections on the evidence presented as it applies to practice or on the essay's central research problem. However, the nature of being introspective about the subject of analysis you have investigated will depend on whether you are explicitly asked to express your observations in this way.

Problems to Avoid

Overgeneralization One of the goals of a case study is to lay a foundation for understanding broader trends and issues applied to similar circumstances. However, be careful when drawing conclusions from your case study. They must be evidence-based and grounded in the results of the study; otherwise, it is merely speculation. Looking at a prior example, it would be incorrect to state that a factor in improving girls access to education in Azerbaijan and the policy implications this may have for improving access in other Muslim nations is due to girls access to social media if there is no documentary evidence from your case study to indicate this. There may be anecdotal evidence that retention rates were better for girls who were engaged with social media, but this observation would only point to the need for further research and would not be a definitive finding if this was not a part of your original research agenda.

Failure to Document Limitations No case is going to reveal all that needs to be understood about a research problem. Therefore, just as you have to clearly state the limitations of a general research study , you must describe the specific limitations inherent in the subject of analysis. For example, the case of studying how women conceptualize the need for water conservation in a village in Uganda could have limited application in other cultural contexts or in areas where fresh water from rivers or lakes is plentiful and, therefore, conservation is understood more in terms of managing access rather than preserving access to a scarce resource.

Failure to Extrapolate All Possible Implications Just as you don't want to over-generalize from your case study findings, you also have to be thorough in the consideration of all possible outcomes or recommendations derived from your findings. If you do not, your reader may question the validity of your analysis, particularly if you failed to document an obvious outcome from your case study research. For example, in the case of studying the accident at the railroad crossing to evaluate where and what types of warning signals should be located, you failed to take into consideration speed limit signage as well as warning signals. When designing your case study, be sure you have thoroughly addressed all aspects of the problem and do not leave gaps in your analysis that leave the reader questioning the results.

Case Studies. Writing@CSU. Colorado State University; Gerring, John. Case Study Research: Principles and Practices . New York: Cambridge University Press, 2007; Merriam, Sharan B. Qualitative Research and Case Study Applications in Education . Rev. ed. San Francisco, CA: Jossey-Bass, 1998; Miller, Lisa L. “The Use of Case Studies in Law and Social Science Research.” Annual Review of Law and Social Science 14 (2018): TBD; Mills, Albert J., Gabrielle Durepos, and Eiden Wiebe, editors. Encyclopedia of Case Study Research . Thousand Oaks, CA: SAGE Publications, 2010; Putney, LeAnn Grogan. "Case Study." In Encyclopedia of Research Design , Neil J. Salkind, editor. (Thousand Oaks, CA: SAGE Publications, 2010), pp. 116-120; Simons, Helen. Case Study Research in Practice . London: SAGE Publications, 2009;  Kratochwill,  Thomas R. and Joel R. Levin, editors. Single-Case Research Design and Analysis: New Development for Psychology and Education .  Hilldsale, NJ: Lawrence Erlbaum Associates, 1992; Swanborn, Peter G. Case Study Research: What, Why and How? London : SAGE, 2010; Yin, Robert K. Case Study Research: Design and Methods . 6th edition. Los Angeles, CA, SAGE Publications, 2014; Walo, Maree, Adrian Bull, and Helen Breen. “Achieving Economic Benefits at Local Events: A Case Study of a Local Sports Event.” Festival Management and Event Tourism 4 (1996): 95-106.

Writing Tip

At Least Five Misconceptions about Case Study Research

Social science case studies are often perceived as limited in their ability to create new knowledge because they are not randomly selected and findings cannot be generalized to larger populations. Flyvbjerg examines five misunderstandings about case study research and systematically "corrects" each one. To quote, these are:

Misunderstanding 1 :  General, theoretical [context-independent] knowledge is more valuable than concrete, practical [context-dependent] knowledge. Misunderstanding 2 :  One cannot generalize on the basis of an individual case; therefore, the case study cannot contribute to scientific development. Misunderstanding 3 :  The case study is most useful for generating hypotheses; that is, in the first stage of a total research process, whereas other methods are more suitable for hypotheses testing and theory building. Misunderstanding 4 :  The case study contains a bias toward verification, that is, a tendency to confirm the researcher’s preconceived notions. Misunderstanding 5 :  It is often difficult to summarize and develop general propositions and theories on the basis of specific case studies [p. 221].

While writing your paper, think introspectively about how you addressed these misconceptions because to do so can help you strengthen the validity and reliability of your research by clarifying issues of case selection, the testing and challenging of existing assumptions, the interpretation of key findings, and the summation of case outcomes. Think of a case study research paper as a complete, in-depth narrative about the specific properties and key characteristics of your subject of analysis applied to the research problem.

Flyvbjerg, Bent. “Five Misunderstandings About Case-Study Research.” Qualitative Inquiry 12 (April 2006): 219-245.

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What Is a Case Study and Why You Should Use Them

Case studies can provide more insights into your business while helping you conduct further research with robust qualitative data analysis to learn more.

If you're in charge of running a company, then you're likely always looking for new ways to run your business more efficiently and increase your customer base while streamlining as many processes as possible.

Unfortunately, it can sometimes be difficult to determine how to go about implementing the proper program in order to be successful. This is why many business owners opt to conduct a case study, which can help significantly. Whether you've been struggling with brand consistency or some other problem, the right case study can identify why your problem exists as well as provide a way to rectify it.

A case study is a great tool that many businesses aren't even aware exists, and there are marketing experts like Mailchimp who can provide you with step-by-step assistance with implementing a plan with a case study. Many companies discover that not only do they need to start a blog in order to improve business, but they also need to create specific and relevant blog titles.

If your company already has a blog, then optimizing your blog posts may be helpful. Regardless of the obstacles that are preventing you from achieving all your professional goals, a case study can work wonders in helping you reverse this issue.

What is a case study?

A case study is a comprehensive report of the results of theory testing or examining emerging themes of a business in real life context. Case studies are also often used in the healthcare industry, conducting health services research with primary research interest around routinely collected healthcare data.

However, for businesses, the purpose of a case study is to help small business owners or company leaders identify the issues and conduct further research into what may be preventing success through information collection, client or customer interviews, and in-depth data analysis.

Knowing the case study definition is crucial for any business owner. By identifying the issues that are hindering a company from achieving all its goals, it's easier to make the necessary corrections to promote success through influenced data collection.

Why are case studies important?

Now that we've answered the questions, "what is a case study?" Why are case studies important? Some of the top reasons why case studies are important include:

• Understand complex issues: Even after you conduct a significant amount of market research , you might have a difficult time understanding exactly what it means. While you might have the basics down, conducting a case study can help you see how that information is applied. Then, when you see how the information can make a difference in business decisions, it could make it easier to understand complex issues.
• Collect data: A case study can also help with data tracking . A case study is a data collection method that can help you describe the information that you have available to you. Then, you can present that information in a way the reader can understand.
• Conduct evaluations: As you learn more about how to write a case study, remember that you can also use a case study to conduct evaluations of a specific situation. A case study is a great way to learn more about complex situations, and you can evaluate how various people responded in that situation. By conducting a case study evaluation, you can learn more about what has worked well, what has not, and what you might want to change in the future.
• Identify potential solutions: A case study can also help you identify solutions to potential problems. If you have an issue in your business that you are trying to solve, you may be able to take a look at a case study where someone has dealt with a similar situation in the past. For example, you may uncover data bias in a specific solution that you would like to address when you tackle the issue on your own. If you need help solving a difficult problem, a case study may be able to help you.

Remember that you can also use case studies to target your audience . If you want to show your audience that you have a significant level of expertise in a field, you may want to publish some case studies that you have handled in the past. Then, when your audience sees that you have had success in a specific area, they may be more likely to provide you with their business. In essence, case studies can be looked at as the original method of social proof, showcasing exactly how you can help someone solve their problems.

What are the benefits of writing a business case study?

Although writing a case study can seem like a tedious task, there are many benefits to conducting one through an in depth qualitative research process.

• Industry understanding: First of all, a case study can give you an in-depth understanding of your industry through a particular conceptual framework and help you identify hidden problems that are preventing you from transcending into the business world.
• Develop theories: If you decide to write a business case study, it provides you with an opportunity to develop new theories. You might have a theory about how to solve a specific problem, but you need to write a business case study to see exactly how that theory has unfolded in the past. Then, you can figure out if you want to apply your theory to a similar issue in the future.
• Evaluate interventions: When you write a business case study that focuses on a specific situation you have been through in the past, you can uncover whether that intervention was truly helpful. This can make it easier to figure out whether you want to use the same intervention in a similar situation in the future.
• Identify best practices: If you want to stay on top of the best practices in your field, conducting case studies can help by allowing you to identify patterns and trends and develop a new list of best practices that you can follow in the future.
• Versatility: Writing a case study also provides you with more versatility. If you want to expand your business applications, you need to figure out how you respond to various problems. When you run a business case study, you open the door to new opportunities, new applications, and new techniques that could help you make a difference in your business down the road.
• Solve problems: Writing a great case study can dramatically improve your chances of reversing your problem and improving your business.
• These are just a few of the biggest benefits you might experience if you decide to publish your case studies. They can be an effective tool for learning, showcasing your talents, and teaching some of your other employees. If you want to grow your audience , you may want to consider publishing some case studies.

What are the limitations of case studies?

Case studies can be a wonderful tool for any business of any size to use to gain an in-depth understanding of their clients, products, customers, or services, but there are limitations.

One limitation of case studies is the fact that, unless there are other recently published examples, there is nothing to compare them to since, most of the time, you are conducting a single, not multiple, case studies.

Another limitation is the fact that most case studies can lack scientific evidence.

Types of case studies

There are specific types of case studies to choose from, and each specific type will yield different results. Some case study types even overlap, which is sometimes more favorable, as they provide even more pertinent data.

Here are overviews of the different types of case studies, each with its own theoretical framework, so you can determine which type would be most effective for helping you meet your goals.

Explanatory case studies

Explanatory case studies are pretty straightforward, as they're not difficult to interpret. This type of case study is best if there aren't many variables involved because explanatory case studies can easily answer questions like "how" and "why" through theory development.

Exploratory case studies

An exploratory case study does exactly what its name implies: it goes into specific detail about the topic at hand in a natural, real-life context with qualitative research.

The benefits of exploratory case studies are limitless, with the main one being that it offers a great deal of flexibility. Having flexibility when writing a case study is important because you can't always predict what obstacles might arise during the qualitative research process.

Collective case studies

Collective case studies require you to study many different individuals in order to obtain usable data.

Case studies that involve an investigation of people will involve many different variables, all of which can't be predicted. Despite this fact, there are many benefits of collective case studies, including the fact that it allows an ongoing analysis of the data collected.

Intrinsic case studies

This type of study differs from the others as it focuses on the inquiry of one specific instance among many possibilities.

Many people prefer these types of case studies because it allows them to learn about the particular instance that they wish to investigate further.

Instrumental case studies

An instrumental case study is similar to an intrinsic one, as it focuses on a particular instance, whether it's a person, organization, or something different.

One thing that differentiates instrumental case studies from intrinsic ones is the fact that instrumental case studies aren't chosen merely because a person is interested in learning about a specific instance.

Tips for writing a case study

If you have decided to write case studies for your company, then you may be unsure of where to start or which type to conduct.

However, it doesn't have to be difficult or confusing to begin conducting a case study that will help you identify ways to improve your business.

Here are some helpful tips for writing your case studies:

1. Your case study must be written in the proper format

When writing a case study, the format that you should be similar to this:

Administrative summary

The executive summary is an overview of what your report will contain, written in a concise manner while providing real-life context.

Despite the fact that the executive summary should appear at the beginning of your case studies, it shouldn't be written until you've completed the entire report because if you write it before you finish the report, this summary may not be completely accurate.

Key problem statement

In this section of your case study, you will briefly describe the problem that you hope to solve by conducting the study. You will have the opportunity to elaborate on the problem that you're focusing on as you get into the breadth of the report.

Problem exploration

This part of the case study isn't as brief as the other two, and it goes into more detail about the problem at hand. Your problem exploration must include why the identified problem needs to be solved as well as the urgency of solving it.

Additionally, it must include justification for conducting the problem-solving, as the benefits must outweigh the efforts and costs.

Proposed resolution

This case study section will also be lengthier than the first two. It must include how you propose going about rectifying the problem. The "recommended solution" section must also include potential obstacles that you might experience, as well as how these will be managed.

Furthermore, you will need to list alternative solutions and explain the reason the chosen solution is best. Charts can enhance your report and make it easier to read, and provide as much proof to substantiate your claim as possible.

Overview of monetary consideration

An overview of monetary consideration is essential for all case studies, as it will be used to convince all involved parties why your project should be funded. You must successfully convince them that the cost is worth the investment it will require. It's important that you stress the necessity for this particular case study and explain the expected outcome.

Execution timeline

In the execution times of case studies, you explain how long you predict it will take to implement your study. The shorter the time it will take to implement your plan, the more apt it is to be approved. However, be sure to provide a reasonable timeline, taking into consideration any additional time that might be needed due to obstacles.

Always include a conclusion in your case study. This is where you will briefly wrap up your entire proposal, stressing the benefits of completing the data collection and data analysis in order to rectify your problem.

2. Make it clear and comprehensive

You want to write your case studies with as much clarity as possible so that every aspect of the report is understood. Be sure to double-check your grammar, spelling, punctuation, and more, as you don't want to submit a poorly-written document.

Not only would a poorly-written case study fail to prove that what you are trying to achieve is important, but it would also increase the chances that your report will be tossed aside and not taken seriously.

3. Don't rush through the process

Writing the perfect case study takes time and patience. Rushing could result in your forgetting to include information that is crucial to your entire study. Don't waste your time creating a study that simply isn't ready. Take the necessary time to perform all the research necessary to write the best case study possible.

Depending on the case study, conducting case study research could mean using qualitative methods, quantitative methods, or both. Qualitative research questions focus on non-numerical data, such as how people feel, their beliefs, their experiences, and so on.

Meanwhile, quantitative research questions focus on numerical or statistical data collection to explain causal links or get an in-depth picture.

It is also important to collect insightful and constructive feedback. This will help you better understand the outcome as well as any changes you need to make to future case studies. Consider using formal and informal ways to collect feedback to ensure that you get a range of opinions and perspectives.

4. Be confident in your theory development

While writing your case study or conducting your formal experimental investigation, you should have confidence in yourself and what you're proposing in your report. If you took the time to gather all the pertinent data collected to complete the report, don't second-guess yourself or doubt your abilities. If you believe your report will be amazing, then it likely will be.

5. Case studies and all qualitative research are long

It's expected that multiple case studies are going to be incredibly boring, and there is no way around this. However, it doesn't mean you can choose your language carefully in order to keep your audience as engaged as possible.

If your audience loses interest in your case study at the beginning, for whatever reason, then this increases the likelihood that your case study will not be funded.

Case study examples

If you want to learn more about how to write a case study, it might be beneficial to take a look at a few case study examples. Below are a few interesting case study examples you may want to take a closer look at.

• Phineas Gage by John Martin Marlow : One of the most famous case studies comes from the medical field, and it is about the story of Phineas Gage, a man who had a railroad spike driven through his head in 1848. As he was working on a railroad, an explosive charge went off prematurely, sending a railroad rod through his head. Even though he survived this incident, he lost his left eye. However, Phineas Gage was studied extensively over the years because his experiences had a significant, lasting impact on his personality. This served as a case study because his injury showed different parts of the brain have different functions.
• Kitty Genovese and the bystander effect : This is a tragic case study that discusses the murder of Kitty Genovese, a woman attacked and murdered in Queens, New York City. Shockingly, while numerous neighbors watched the scene, nobody called for help because they assumed someone else would. This case study helped to define the bystander effect, which is when a person fails to intervene during an emergency because other people are around.
• Henry Molaison and the study of memory : Henry Molaison lost his memory and suffered from debilitating amnesia. He suffered from childhood epilepsy, and medical professionals attempted to remove the part of his brain that was causing his seizures. He had a portion of his brain removed, but it completely took away his ability to hold memories. Even though he went on to live until the age of 82, he was always forced to live in the present moment, as he was completely unable to form new memories.

Case study FAQs

When should you do a case study.

There are several scenarios when conducting a case study can be beneficial. Case studies are often used when there's a "why" or "how" question that needs to be answered. Case studies are also beneficial when trying to understand a complex phenomenon, there's limited research on a topic, or when you're looking for practical solutions to a problem.

How can case study results be used to make business decisions?

You can use the results from a case study to make future business decisions if you find yourself in a similar situation. As you assess the results of a case study, you can identify best practices, evaluate the effectiveness of an intervention, generate new and creative ideas, or get a better understanding of customer needs.

How are case studies different from other research methodologies?

When compared to other research methodologies, such as experimental or qualitative research methodology, a case study does not require a representative sample. For example, if you are performing quantitative research, you have a lot of subjects that expand your sample size. If you are performing experimental research, you may have a random sample in front of you. A case study is usually designed to deliberately focus on unusual situations, which allows it to shed new light on a specific business research problem.

Writing multiple case studies for your business

If you're feeling overwhelmed by the idea of writing a case study and it seems completely foreign, then you aren't alone. Writing a case study for a business is a very big deal, but fortunately, there is help available because an example of a case study doesn't always help.

Mailchimp, a well-known marketing company that provides comprehensive marketing support for all sorts of businesses, can assist you with your case study, or you can review one of their own recently published examples.

Mailchimp can assist you with developing the most effective content strategy to increase your chances of being as successful as possible. Mailchimp's content studio is a great tool that can help your business immensely.

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Blog Beginner Guides What is a Case Study? [+6 Types of Case Studies]

What is a Case Study? [+6 Types of Case Studies]

Written by: Ronita Mohan Sep 20, 2021

Case studies have become powerful business tools. But what is a case study? What are the benefits of creating one? Are there limitations to the format?

If you’ve asked yourself these questions, our helpful guide will clear things up. Learn how to use a case study for business. Find out how cases analysis works in psychology and research.

We’ve also got examples of case studies to inspire you.

Haven’t made a case study before? You can easily  create a case study  with Venngage’s customizable templates.

Click to jump ahead:

What is a case study, what is the case study method, benefits of case studies, limitations of case studies, types of case studies, faqs about case studies.

Case studies are research methodologies. They examine subjects, projects, or organizations to tell a story.

Numerous sectors use case analyses. The social sciences, social work, and psychology create studies regularly.

Healthcare industries write reports on patients and diagnoses. Marketing case study examples , like the one below, highlight the benefits of a business product.

Now that you know what a case study is, we explain how case reports are used in three different industries.

What is a business case study?

A business or marketing case study aims at showcasing a successful partnership. This can be between a brand and a client. Or the case study can examine a brand’s project.

There is a perception that case studies are used to advertise a brand. But effective reports, like the one below, can show clients how a brand can support them.

Hubspot created a case study on a customer that successfully scaled its business. The report outlines the various Hubspot tools used to achieve these results.

Hubspot also added a video with testimonials from the client company’s employees.

So, what is the purpose of a case study for businesses? There is a lot of competition in the corporate world. Companies are run by people. They can be on the fence about which brand to work with.

Business reports  stand out aesthetically, as well. They use  brand colors  and brand fonts . Usually, a combination of the client’s and the brand’s.

With the Venngage  My Brand Kit  feature, businesses can automatically apply their brand to designs.

A business case study, like the one below, acts as social proof. This helps customers decide between your brand and your competitors.

Don’t know how to design a report? You can learn  how to write a case study  with Venngage’s guide. We also share design tips and examples that will help you convert.

Related: 55+ Annual Report Design Templates, Inspirational Examples & Tips [Updated]

What is a case study in psychology?

In the field of psychology, case studies focus on a particular subject. Psychology case histories also examine human behaviors.

Case reports search for commonalities between humans. They are also used to prescribe further research. Or these studies can elaborate on a solution for a behavioral ailment.

The American Psychology Association  has a number of case studies on real-life clients. Note how the reports are more text-heavy than a business case study.

Famous psychologists such as Sigmund Freud and Anna O popularised the use of case studies in the field. They did so by regularly interviewing subjects. Their detailed observations build the field of psychology.

It is important to note that psychological studies must be conducted by professionals. Psychologists, psychiatrists and therapists should be the researchers in these cases.

Related: What Netflix’s Top 50 Shows Can Teach Us About Font Psychology [Infographic]

What is a case study in research?

Research is a necessary part of every case study. But specific research fields are required to create studies. These fields include user research, healthcare, education, or social work.

For example, this UX Design  report examined the public perception of a client. The brand researched and implemented new visuals to improve it. The study breaks down this research through lessons learned.

Clinical reports are a necessity in the medical field. These documents are used to share knowledge with other professionals. They also help examine new or unusual diseases or symptoms.

The pandemic has led to a significant increase in research. For example,  Spectrum Health  studied the value of health systems in the pandemic. They created the study by examining community outreach.

The pandemic has significantly impacted the field of education. This has led to numerous examinations on remote studying. There have also been studies on how students react to decreased peer communication.

Social work case reports often have a community focus. They can also examine public health responses. In certain regions, social workers study disaster responses.

You now know what case studies in various fields are. In the next step of our guide, we explain the case study method.

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A case analysis is a deep dive into a subject. To facilitate this case studies are built on interviews and observations. The below example would have been created after numerous interviews.

Case studies are largely qualitative. They analyze and describe phenomena. While some data is included, a case analysis is not quantitative.

There are a few steps in the case method. You have to start by identifying the subject of your study. Then determine what kind of research is required.

In natural sciences, case studies can take years to complete. Business reports, like this one, don’t take that long. A few weeks of interviews should be enough.

The case method will vary depending on the industry. Reports will also look different once produced.

As you will have seen, business reports are more colorful. The design is also more accessible . Healthcare and psychology reports are more text-heavy.

Designing case reports takes time and energy. So, is it worth taking the time to write them? Here are the benefits of creating case studies.

• Collects large amounts of information
• Helps formulate hypotheses
• Builds the case for further research
• Discovers new insights into a subject
• Builds brand trust and loyalty
• Engages customers through stories

For example, the business study below creates a story around a brand partnership. It makes for engaging reading. The study also shows evidence backing up the information.

We’ve shared the benefits of why studies are needed. We will also look at the limitations of creating them.

Related: How to Present a Case Study like a Pro (With Examples)

There are a few disadvantages to conducting a case analysis. The limitations will vary according to the industry.

• Responses from interviews are subjective
• Subjects may tailor responses to the researcher
• Studies can’t always be replicated
• In certain industries, analyses can take time and be expensive
• Risk of generalizing the results among a larger population

These are some of the common weaknesses of creating case reports. If you’re on the fence, look at the competition in your industry.

Other brands or professionals are building reports, like this example. In that case, you may want to do the same.

There are six common types of case reports. Depending on your industry, you might use one of these types.

Descriptive case studies

Explanatory case studies, exploratory case reports, intrinsic case studies, instrumental case studies, collective case reports.

We go into more detail about each type of study in the guide below.

Related:  15+ Professional Case Study Examples [Design Tips + Templates]

When you have an existing hypothesis, you can design a descriptive study. This type of report starts with a description. The aim is to find connections between the subject being studied and a theory.

Once these connections are found, the study can conclude. The results of this type of study will usually suggest how to develop a theory further.

A study like the one below has concrete results. A descriptive report would use the quantitative data as a suggestion for researching the subject deeply.

When an incident occurs in a field, an explanation is required. An explanatory report investigates the cause of the event. It will include explanations for that cause.

The study will also share details about the impact of the event. In most cases, this report will use evidence to predict future occurrences. The results of explanatory reports are definitive.

Note that there is no room for interpretation here. The results are absolute.

The study below is a good example. It explains how one brand used the services of another. It concludes by showing definitive proof that the collaboration was successful.

Another example of this study would be in the automotive industry. If a vehicle fails a test, an explanatory study will examine why. The results could show that the failure was because of a particular part.

Related: How to Write a Case Study [+ Design Tips]

An explanatory report is a self-contained document. An exploratory one is only the beginning of an investigation.

Exploratory cases act as the starting point of studies. This is usually conducted as a precursor to large-scale investigations. The research is used to suggest why further investigations are needed.

An exploratory study can also be used to suggest methods for further examination.

For example, the below analysis could have found inconclusive results. In that situation, it would be the basis for an in-depth study.

Intrinsic studies are more common in the field of psychology. These reports can also be conducted in healthcare or social work.

These types of studies focus on a unique subject, such as a patient. They can sometimes study groups close to the researcher.

The aim of such studies is to understand the subject better. This requires learning their history. The researcher will also examine how they interact with their environment.

For instance, if the case study below was about a unique brand, it could be an intrinsic study.

Once the study is complete, the researcher will have developed a better understanding of a phenomenon. This phenomenon will likely not have been studied or theorized about before.

Examples of intrinsic case analysis can be found across psychology. For example, Jean Piaget’s theories on cognitive development. He established the theory from intrinsic studies into his own children.

Related: What Disney Villains Can Tell Us About Color Psychology [Infographic]

This is another type of study seen in medical and psychology fields. Instrumental reports are created to examine more than just the primary subject.

When research is conducted for an instrumental study, it is to provide the basis for a larger phenomenon. The subject matter is usually the best example of the phenomenon. This is why it is being studied.

Take the example of the fictional brand below.

Assume it’s examining lead generation strategies. It may want to show that visual marketing is the definitive lead generation tool. The brand can conduct an instrumental case study to examine this phenomenon.

Collective studies are based on instrumental case reports. These types of studies examine multiple reports.

There are a number of reasons why collective reports are created:

• To provide evidence for starting a new study
• To find pattens between multiple instrumental reports
• To find differences in similar types of cases
• Gain a deeper understanding of a complex phenomenon
• Understand a phenomenon from diverse contexts

A researcher could use multiple reports, like the one below, to build a collective case report.

Related: 10+ Case Study Infographic Templates That Convert

What makes a case study a case study?

A case study has a very particular research methodology. They are an in-depth study of a person or a group of individuals. They can also study a community or an organization. Case reports examine real-world phenomena within a set context.

How long should a case study be?

The length of studies depends on the industry. It also depends on the story you’re telling. Most case studies should be at least 500-1500 words long. But you can increase the length if you have more details to share.

What should you ask in a case study?

The one thing you shouldn’t ask is ‘yes’ or ‘no’ questions. Case studies are qualitative. These questions won’t give you the information you need.

Ask your client about the problems they faced. Ask them about solutions they found. Or what they think is the ideal solution. Leave room to ask them follow-up questions. This will help build out the study.

How to present a case study?

When you’re ready to present a case study, begin by providing a summary of the problem or challenge you were addressing. Follow this with an outline of the solution you implemented, and support this with the results you achieved, backed by relevant data. Incorporate visual aids like slides, graphs, and images to make your case study presentation more engaging and impactful.

Now you know what a case study means, you can begin creating one. These reports are a great tool for analyzing brands. They are also useful in a variety of other fields.

Use a visual communication platform like Venngage to design case studies. With Venngage’s templates, you can design easily. Create branded, engaging reports, all without design experience.

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What the Case Study Method Really Teaches

• Nitin Nohria

Seven meta-skills that stick even if the cases fade from memory.

It’s been 100 years since Harvard Business School began using the case study method. Beyond teaching specific subject matter, the case study method excels in instilling meta-skills in students. This article explains the importance of seven such skills: preparation, discernment, bias recognition, judgement, collaboration, curiosity, and self-confidence.

During my decade as dean of Harvard Business School, I spent hundreds of hours talking with our alumni. To enliven these conversations, I relied on a favorite question: “What was the most important thing you learned from your time in our MBA program?”

• Nitin Nohria is the George F. Baker Jr. and Distinguished Service University Professor. He served as the 10th dean of Harvard Business School, from 2010 to 2020.

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Undergraduate vs. Graduate: Educate Yourself On The Difference

• Undergraduate Meaning
• Undergraduate Student And Degree
• Graduate Meaning
• Graduate Degree And Student
• Graduate Origin
• Postgraduate Meaning

⚡ Quick summary

The main difference between undergraduate and graduate is that undergraduate is always used in the context of the first level of college or university education (the level where you can earn a bachelor’s degree ). In terms like graduate student and graduate degree , graduate refers to a level of advanced education beyond the undergraduate level, especially a master’s degree or doctorate . The noun graduate is more general, simply referring to a person who has completed a level of education (someone who has graduated ).

The difference between undergraduate and graduate is a difference of degrees (*throws graduation cap in the air to celebrate the pun*).

The level of education that each word involves varies depending on how the word is being used, and there are situations in which both words can be used in the same situation. For example, you can become a graduate student after graduating with an undergraduate degree.

The word graduate can mean very different things depending on whether it’s used as a noun (as in recent   high school graduates ), an adjective (as in graduate student and graduate degree ), or a verb (as in I plan to graduate next May ). The same goes for its shortened form, grad , which can be used as a noun (as in Congrats, grads! ) or an adjective (as in grad program ).

Undergraduate can also be used both as a noun (as in I’m an undergraduate at Stanford University ) or an adjective (as in I’m working toward my undergraduate degree ). It can be shortened to undergrad in both cases.

By the end of this article, you’ll have an advanced degree in all the different ways graduate, grad , undergraduate , and undergrad are used, and what they mean in each case.

What does undergraduate mean?

An undergraduate is “a student in a university or college who has not received a first, especially a bachelor’s, degree.” For example, a college student might say I’m an undergraduate at the University of Texas if they were pursuing a bachelor’s degree there.

Undergraduate is also commonly used as an adjective in this same context, in terms like undergraduate student , undergraduate degree , and undergraduate studies.

Undergraduate is often shortened to undergrad as both a noun and an adjective.

In undergraduate, the prefix under- is used to indicate a lower rank or status. The educational status of an undergraduate student is below that of a graduate student.

What’s the difference between wisdom and knowledge ? Here’s a lesson on the two terms.

What is an undergraduate student ? And what is an undergraduate degree ?

An undergraduate student is a student who is pursuing a degree at the first level of higher education (meaning the level after high school) at a college or university. Undergraduate students are typically those working to earn a bachelor’s degree (or, less commonly, an associate’s degree ). These degrees are often referred to with the general term undergraduate degree.

Outside of the US, an undergraduate degree is sometimes called a first degree. There are also other types of undergraduate degrees outside of the US, such as a foundation degree (which, like an associate’s degree, is typically a two-year degree).

What does graduate mean?

As a noun, the word graduate  [  graj -oo-it ] refers to “a person who has received a degree or diploma on completing a course of study.” In other words, a graduate is someone who has completed a particular level of schooling or an educational program—a child who just finished kindergarten and a doctor who just completed medical school are both graduates. It can even be used figuratively , as in She’s a graduate of the school of hard knocks.

As a verb, graduate [  graj -oo-eyt ] means “to receive a degree or diploma on completing a course of study.” The process of graduating—and the ceremony itself—is called graduation .

As an adjective, graduate [  graj -oo-it ] means something more specific. It’s used to indicate that a student, degree, or educational program is an advanced one, beyond the level of a bachelor’s degree. This sense of graduate is most commonly used in terms like graduate degree, graduate school , graduate program, and graduate student.

What is a graduate degree ? And what is a graduate student ?

Graduate degree typically refers to a degree beyond a bachelor’s, most commonly a master’s.

A graduate student is a student who’s pursuing an advanced degree after having earned their undergraduate degree (such as a bachelor’s degree) by graduating from an undergraduate program. Calling someone a graduate student most often means they are pursuing their master’s degree, but it may be another advanced degree, such as a PhD (You’d most commonly call such students PhD students. Or you might say they are working toward their doctorate or their doctoral degree.)

To earn a graduate degree, graduate students go to a division of a university known as graduate school , and such a program is often called a graduate program. In all of these terms, graduate is often shortened to grad : grad school , grad student , grad program . (A student doesn’t become a graduate student until they take graduate-level courses. For example, if a student graduates with a bachelor’s degree and then later pursues a different bachelor’s degree, they are still an undergraduate student .)

Some graduate studies are referred to in more specific ways: medical students go to medical school to earn their medical degree ; law students go to law school to earn their law degree.

Do you know the difference between these highly-esteemed graduate degrees and titles: PhD, MD, and Dr ?

Where does the word graduate come from?

Graduate comes from the Medieval Latin graduārī, meaning “to take a degree.” It ultimately derives from the Latin gradus, meaning “a step.” Each time you graduate, you take a step to the next level of education.

What does postgraduate mean?

The adjective postgraduate is sometimes used in the same way as the adjective sense of the word graduate, especially in the UK, as in postgraduate student or postgraduate studies.

Postgraduate should not be confused with postdoctoral , which refers to studies, research, or professional work above the level of a doctorate.

How to use undergraduate vs. graduate

The best way to sort out the different meanings of undergraduate and graduate is to determine whether each word is being used as a noun, an adjective, or a verb. Here’s an easy breakdown of the differences.

• undergraduate (noun): A college student pursuing a non-advanced degree, most commonly a bachelor’s degree. Can be shortened to undergrad.
• undergraduate (adjective): Used in the context of colleges and university programs ( undergraduate programs ) where students are pursuing a degree (generally referred to as an undergraduate degree ) that is not an advanced degree. Also sometimes shortened to undergrad.
• graduate (noun): A person who has completed a particular level of schooling or educational program. Can be shortened to grad.
• graduate (verb): To complete a level of schooling (and, typically, to receive a degree or diploma). You can graduate from kindergarten, high school, college, graduate school, medical school, etc.
• graduate (adjective): Used in the context of advanced schooling—a level beyond a bachelor’s degree, most commonly a master’s program. Used in terms like graduate student , graduate school , graduate degree , graduate program , graduate courses , etc. Often shortened to grad.

Examples of undergraduate, undergrad, graduate, and grad used in a sentence

Let’s look at some examples of these words in actual, real-life use to get the meanings straight.

• As an undergraduate, she had studied engineering; as a graduate student, she switched to architecture.
• I completed my undergraduate degree after five years and a lot of hard work.
• As a graduate student, you will be expected to complete a thesis.
• You should start thinking about graduate school applications before you graduate.
• Most of the applicants for this position are recent college graduates.
• I’m still an undergrad, but I’m hoping to start grad school next fall.
• I’m a UGA grad, but I almost went to Georgia Tech.

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No matter who is graduating, here are tips on how to craft a perfect congratulations card for their achievement.

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The state of AI in early 2024: Gen AI adoption spikes and starts to generate value

If 2023 was the year the world discovered generative AI (gen AI) , 2024 is the year organizations truly began using—and deriving business value from—this new technology. In the latest McKinsey Global Survey  on AI, 65 percent of respondents report that their organizations are regularly using gen AI, nearly double the percentage from our previous survey just ten months ago. Respondents’ expectations for gen AI’s impact remain as high as they were last year , with three-quarters predicting that gen AI will lead to significant or disruptive change in their industries in the years ahead.

About the authors

This article is a collaborative effort by Alex Singla , Alexander Sukharevsky , Lareina Yee , and Michael Chui , with Bryce Hall , representing views from QuantumBlack, AI by McKinsey, and McKinsey Digital.

Organizations are already seeing material benefits from gen AI use, reporting both cost decreases and revenue jumps in the business units deploying the technology. The survey also provides insights into the kinds of risks presented by gen AI—most notably, inaccuracy—as well as the emerging practices of top performers to mitigate those challenges and capture value.

AI adoption surges

Interest in generative AI has also brightened the spotlight on a broader set of AI capabilities. For the past six years, AI adoption by respondents’ organizations has hovered at about 50 percent. This year, the survey finds that adoption has jumped to 72 percent (Exhibit 1). And the interest is truly global in scope. Our 2023 survey found that AI adoption did not reach 66 percent in any region; however, this year more than two-thirds of respondents in nearly every region say their organizations are using AI. 1 Organizations based in Central and South America are the exception, with 58 percent of respondents working for organizations based in Central and South America reporting AI adoption. Looking by industry, the biggest increase in adoption can be found in professional services. 2 Includes respondents working for organizations focused on human resources, legal services, management consulting, market research, R&D, tax preparation, and training.

Also, responses suggest that companies are now using AI in more parts of the business. Half of respondents say their organizations have adopted AI in two or more business functions, up from less than a third of respondents in 2023 (Exhibit 2).

Gen AI adoption is most common in the functions where it can create the most value

Most respondents now report that their organizations—and they as individuals—are using gen AI. Sixty-five percent of respondents say their organizations are regularly using gen AI in at least one business function, up from one-third last year. The average organization using gen AI is doing so in two functions, most often in marketing and sales and in product and service development—two functions in which previous research  determined that gen AI adoption could generate the most value 3 “ The economic potential of generative AI: The next productivity frontier ,” McKinsey, June 14, 2023. —as well as in IT (Exhibit 3). The biggest increase from 2023 is found in marketing and sales, where reported adoption has more than doubled. Yet across functions, only two use cases, both within marketing and sales, are reported by 15 percent or more of respondents.

Gen AI also is weaving its way into respondents’ personal lives. Compared with 2023, respondents are much more likely to be using gen AI at work and even more likely to be using gen AI both at work and in their personal lives (Exhibit 4). The survey finds upticks in gen AI use across all regions, with the largest increases in Asia–Pacific and Greater China. Respondents at the highest seniority levels, meanwhile, show larger jumps in the use of gen Al tools for work and outside of work compared with their midlevel-management peers. Looking at specific industries, respondents working in energy and materials and in professional services report the largest increase in gen AI use.

Investments in gen AI and analytical AI are beginning to create value

The latest survey also shows how different industries are budgeting for gen AI. Responses suggest that, in many industries, organizations are about equally as likely to be investing more than 5 percent of their digital budgets in gen AI as they are in nongenerative, analytical-AI solutions (Exhibit 5). Yet in most industries, larger shares of respondents report that their organizations spend more than 20 percent on analytical AI than on gen AI. Looking ahead, most respondents—67 percent—expect their organizations to invest more in AI over the next three years.

Where are those investments paying off? For the first time, our latest survey explored the value created by gen AI use by business function. The function in which the largest share of respondents report seeing cost decreases is human resources. Respondents most commonly report meaningful revenue increases (of more than 5 percent) in supply chain and inventory management (Exhibit 6). For analytical AI, respondents most often report seeing cost benefits in service operations—in line with what we found last year —as well as meaningful revenue increases from AI use in marketing and sales.

Inaccuracy: The most recognized and experienced risk of gen AI use

As businesses begin to see the benefits of gen AI, they’re also recognizing the diverse risks associated with the technology. These can range from data management risks such as data privacy, bias, or intellectual property (IP) infringement to model management risks, which tend to focus on inaccurate output or lack of explainability. A third big risk category is security and incorrect use.

Respondents to the latest survey are more likely than they were last year to say their organizations consider inaccuracy and IP infringement to be relevant to their use of gen AI, and about half continue to view cybersecurity as a risk (Exhibit 7).

Conversely, respondents are less likely than they were last year to say their organizations consider workforce and labor displacement to be relevant risks and are not increasing efforts to mitigate them.

In fact, inaccuracy— which can affect use cases across the gen AI value chain , ranging from customer journeys and summarization to coding and creative content—is the only risk that respondents are significantly more likely than last year to say their organizations are actively working to mitigate.

Some organizations have already experienced negative consequences from the use of gen AI, with 44 percent of respondents saying their organizations have experienced at least one consequence (Exhibit 8). Respondents most often report inaccuracy as a risk that has affected their organizations, followed by cybersecurity and explainability.

Our previous research has found that there are several elements of governance that can help in scaling gen AI use responsibly, yet few respondents report having these risk-related practices in place. 4 “ Implementing generative AI with speed and safety ,” McKinsey Quarterly , March 13, 2024. For example, just 18 percent say their organizations have an enterprise-wide council or board with the authority to make decisions involving responsible AI governance, and only one-third say gen AI risk awareness and risk mitigation controls are required skill sets for technical talent.

Bringing gen AI capabilities to bear

The latest survey also sought to understand how, and how quickly, organizations are deploying these new gen AI tools. We have found three archetypes for implementing gen AI solutions : takers use off-the-shelf, publicly available solutions; shapers customize those tools with proprietary data and systems; and makers develop their own foundation models from scratch. 5 “ Technology’s generational moment with generative AI: A CIO and CTO guide ,” McKinsey, July 11, 2023. Across most industries, the survey results suggest that organizations are finding off-the-shelf offerings applicable to their business needs—though many are pursuing opportunities to customize models or even develop their own (Exhibit 9). About half of reported gen AI uses within respondents’ business functions are utilizing off-the-shelf, publicly available models or tools, with little or no customization. Respondents in energy and materials, technology, and media and telecommunications are more likely to report significant customization or tuning of publicly available models or developing their own proprietary models to address specific business needs.

Respondents most often report that their organizations required one to four months from the start of a project to put gen AI into production, though the time it takes varies by business function (Exhibit 10). It also depends upon the approach for acquiring those capabilities. Not surprisingly, reported uses of highly customized or proprietary models are 1.5 times more likely than off-the-shelf, publicly available models to take five months or more to implement.

Gen AI high performers are excelling despite facing challenges

Gen AI is a new technology, and organizations are still early in the journey of pursuing its opportunities and scaling it across functions. So it’s little surprise that only a small subset of respondents (46 out of 876) report that a meaningful share of their organizations’ EBIT can be attributed to their deployment of gen AI. Still, these gen AI leaders are worth examining closely. These, after all, are the early movers, who already attribute more than 10 percent of their organizations’ EBIT to their use of gen AI. Forty-two percent of these high performers say more than 20 percent of their EBIT is attributable to their use of nongenerative, analytical AI, and they span industries and regions—though most are at organizations with less than $1 billion in annual revenue. The AI-related practices at these organizations can offer guidance to those looking to create value from gen AI adoption at their own organizations.

To start, gen AI high performers are using gen AI in more business functions—an average of three functions, while others average two. They, like other organizations, are most likely to use gen AI in marketing and sales and product or service development, but they’re much more likely than others to use gen AI solutions in risk, legal, and compliance; in strategy and corporate finance; and in supply chain and inventory management. They’re more than three times as likely as others to be using gen AI in activities ranging from processing of accounting documents and risk assessment to R&D testing and pricing and promotions. While, overall, about half of reported gen AI applications within business functions are utilizing publicly available models or tools, gen AI high performers are less likely to use those off-the-shelf options than to either implement significantly customized versions of those tools or to develop their own proprietary foundation models.

What else are these high performers doing differently? For one thing, they are paying more attention to gen-AI-related risks. Perhaps because they are further along on their journeys, they are more likely than others to say their organizations have experienced every negative consequence from gen AI we asked about, from cybersecurity and personal privacy to explainability and IP infringement. Given that, they are more likely than others to report that their organizations consider those risks, as well as regulatory compliance, environmental impacts, and political stability, to be relevant to their gen AI use, and they say they take steps to mitigate more risks than others do.

Gen AI high performers are also much more likely to say their organizations follow a set of risk-related best practices (Exhibit 11). For example, they are nearly twice as likely as others to involve the legal function and embed risk reviews early on in the development of gen AI solutions—that is, to “ shift left .” They’re also much more likely than others to employ a wide range of other best practices, from strategy-related practices to those related to scaling.

In addition to experiencing the risks of gen AI adoption, high performers have encountered other challenges that can serve as warnings to others (Exhibit 12). Seventy percent say they have experienced difficulties with data, including defining processes for data governance, developing the ability to quickly integrate data into AI models, and an insufficient amount of training data, highlighting the essential role that data play in capturing value. High performers are also more likely than others to report experiencing challenges with their operating models, such as implementing agile ways of working and effective sprint performance management.

About the research

The online survey was in the field from February 22 to March 5, 2024, and garnered responses from 1,363 participants representing the full range of regions, industries, company sizes, functional specialties, and tenures. Of those respondents, 981 said their organizations had adopted AI in at least one business function, and 878 said their organizations were regularly using gen AI in at least one function. To adjust for differences in response rates, the data are weighted by the contribution of each respondent’s nation to global GDP.

Alex Singla and Alexander Sukharevsky  are global coleaders of QuantumBlack, AI by McKinsey, and senior partners in McKinsey’s Chicago and London offices, respectively; Lareina Yee  is a senior partner in the Bay Area office, where Michael Chui , a McKinsey Global Institute partner, is a partner; and Bryce Hall  is an associate partner in the Washington, DC, office.

They wish to thank Kaitlin Noe, Larry Kanter, Mallika Jhamb, and Shinjini Srivastava for their contributions to this work.

This article was edited by Heather Hanselman, a senior editor in McKinsey’s Atlanta office.

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Measuring myofascial shear strain in chronic shoulder pain with ultrasound shear strain imaging: a case report

• Lingyi Zhao 1 ,
• Jonny Huang 2 ,
• Muyinatu A. Lediju Bell 1 , 3 , 4 &
• Preeti Raghavan 2  

BMC Musculoskeletal Disorders volume  25 , Article number:  412 ( 2024 ) Cite this article

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Dysfunctional gliding of deep fascia and muscle layers forms the basis of myofascial pain and dysfunction, which can cause chronic shoulder pain. Ultrasound shear strain imaging may offer a non-invasive tool to quantitatively evaluate the extent of muscular dysfunctional gliding and its correlation with pain. This case study is the first to use ultrasound shear strain imaging to report the shear strain between the pectoralis major and minor muscles in shoulders with and without chronic pain.

Case presentation

The shear strain between the pectoralis major and minor muscles during shoulder rotation in a volunteer with chronic shoulder pain was measured with ultrasound shear strain imaging. The results show that the mean ± standard deviation shear strain was 0.40 ± 0.09 on the affected side, compared to 1.09 ± 0.18 on the unaffected side ( p <0.05). The results suggest that myofascial dysfunction may cause the muscles to adhere together thereby reducing shear strain on the affected side.

Our findings elucidate a potential pathophysiology of myofascial dysfunction in chronic shoulder pain and reveal the potential utility of ultrasound imaging to provide a useful biomarker for shear strain evaluation between the pectoralis major and minor muscles.

Peer Review reports

Shoulder pain can have various causes, one of which is myofascial pain and dysfunction [ 1 ]. The myofascial system comprises contractile muscle and connective tissue. The connective tissue creates the muscle shape, penetrates the muscle, orients the nerve and vascular endings, and transmits movement from the muscles to the bones to which they are attached [ 2 ]. Myofascial pain is characterized by the presence of muscular trigger points (TP), which are hard, palpable nodules located within taut bands in skeletal muscle [ 3 , 4 ]. Although the cause of myofascial pain is not fully understood, one hypothesis is that any change in the mechano-metabolic environment that produces aggregation of hyaluronan (HA) in the intra- and/or inter-muscular extracellular matrix (ECM) can make the fascia more viscous [ 2 ]. This can result in dysfunctional gliding of deep fascia and muscle layers, forming the basis of myofascial pain [ 5 ]. Deep or muscular fascia consists of precisely organized, dense, fibrous layers of collagen, elastin, and hyaluronan that interface intricately with the musculature. This enables muscular force to be transmitted efficiently across and between muscles [ 6 ].

As a non-invasive and real-time imaging tool, ultrasound (US) imaging can be important in evaluating dysfunctional gliding of muscles [ 7 ]. By obtaining real-time visualization of tissue structures and their movements, US imaging can enable clinicians to observe how the muscles and other tissues behave during various movements, which can greatly aid in identifying and assessing dysfunctional gliding.

The most common sonographic findings in patients with myofascial pain are myofascial trigger points, which usually present as hypoechoic nodules within the muscle tissue [ 8 ]. In addition, compressing the hypoechoic myofascial trigger point with the US transducer may promptly reproduce the pain (positive sono-palpation). Sonographic mapping of myofascial trigger points can aid accurate and safe intervention techniques such as needling and injection [ 8 ].

Combined with dynamic US imaging, shear strain mapping focuses on measuring the deformation or displacement of tissues under mechanical stress or during movement. A previous study has shown that shear strain mapping can quantitatively evaluate the extent of dysfunctional gliding and its correlation with pain [ 7 ].

In this case report, we used US shear strain mapping to quantify inter-layer relative motion between the pectoralis major (PMA) and pectoralis minor (PMI) muscles in a volunteer with chronic pain in the left shoulder (i.e., the affected side). We examined the interface between these muscles because tightness in these muscles leads to altered movement of the scapula [ 9 , 10 , 11 ]. Furthermore, tightness in the pectoral muscles impedes shoulder internal and external rotation [ 12 , 13 , 14 ].

The volunteer performed shoulder external rotation passively using a bimanual arm trainer during which movement of the pectoral muscles was imaged dynamically using ultrasonography. The shear strain between the PMA and PMI muscles was measured and compared between the affected and the unaffected sides.

The remaining contents of this case report are organized as follows: The Case presentation  section describes the patient history, experiment setup, measurement methods, and measurement results. The  Discussion  section contextualizes our key findings, limitations, and future directions. The  Conclusions  section summarizes the case report.

Patient history

The volunteer reported in our study is a 49-year-old woman with chronic pain in her left shoulder for the past two years, reported as 5-6/10 on a numeric rating scale. The pain was exacerbated on arm elevation and lifting heavy objects and was episodic. She noted that the pain was accompanied by tightness in the anterior aspect of the chest. It was relieved with heat, stretching, and occasional use of analgesics (acetaminophen). Physical examination revealed normal range of motion at the shoulder passively. A pain level of 6/10 was elicited on the left shoulder compared to 0/10 on the right shoulder on active shoulder external rotation and elevation. Strength testing in the shoulder muscles was limited by pain.

We used a bimanual arm training device (Fig. 1 a) to repeatedly move the volunteer’s left (affected side) or right (unaffected) arm into shoulder external rotation at a rate of 0.5 Hz. Figure 1 b provides a visualization of the anatomical locations of the pectoralis minor (PMI) and pectoralis major (PMA) muscles we examined. We used the bimanual arm trainer because it is an FDA-cleared device designed specifically to provide gentle, controlled passive external rotation at the shoulder, which is especially useful when one shoulder is impaired [ 15 ]. The external rotation started from a position of full internal rotation to 30 \(^{\circ }\) of external rotation for each cycle. The arm was abducted to 30 \(^{\circ }\) , and the forearm and wrist rested in a neutral position on the arm trough of the device. Passive external rotation in this position using the bimanual arm trainer did not elicit shoulder pain, making the examination relatively comfortable. We acquired a US cine loop (24 Hz) over at least five full rotation cycles using a Clarius L15 scanner (Vancouver, BC, Canada), which is a wireless linear ultrasound transducer with an acoustic frequency range of 5-15 MHz. The transducer was stabilized by a Sawyer robot (Bochum, NRW, Germany) and placed to access the longitudinal plane of the pectoralis muscles. US cine loops of both the affected and unaffected sides were acquired.

a Bimanual arm training device used to move the volunteer’s arms repeatedly. b Anatomical locations of the pectoralis minor (PMI) and pectoralis major (PMA) muscles. The yellow rectangle indicates the position of the ultrasound transducer, with ‘L’ denoting the left side of the transducer

Next, we used a cross-correlation-based speckle tracking technique [ 16 ] to estimate the inter-frame lateral and axial displacements. Two regions of interest (ROI) with the same lateral location were manually selected on the B-mode image at the beginning of the rotation for movement tracking. The first ROI included the PMI muscle, and the second ROI included the PMA muscle in front of the PMI muscle. The hyperechoic fascial plane was used to delineate the lower boundary of the PMA muscle and the upper boundary of the PMI muscle. For both the affected and unaffected sides, the ROI of the PMA muscle had a size of 6.76 mm \(\times\) 2.18 mm, the ROI of the PMI muscle had a size of 6.76 mm \(\times\) 2.13 mm, and the distance between the centers of the two ROIs was 2.16 mm. The ROI of the PMA muscle and the PMI muscle will be referred to as PMA ROI and PMI ROI, respectively, for brevity. Although the predominant motion of PMA ROI and PMI ROI during rotation is lateral in the longitudinal view, a small amount of axial tissue motion can also occur. To correct for any axial displacement, we adjusted the inter-frame lateral displacement of the two ROIs based on axial displacement maps. The final inter-frame lateral displacements of the two ROIs were determined after this adjustment. Our displacement estimation approach was tested on simulated and experimental phantom data with known ground truths to ensure the reliability of associated displacement and strain assessments [ 16 , 17 ].

The average inter-frame displacements associated with the PMA and PMI ROIs were temporally accumulated to obtain the cumulative displacements. The lateral shear strain between the PMI ROI and PMA ROI is defined as:

where \(M_{PMA}\) is the lateral displacement of PMA ROI, \(M_{PMI}\) is the lateral displacement of PMI ROI, and D is the distance between the centers of the two ROIs. The sign of the calculated shear strain represents direction rather than magnitude.

To quantitatively compare the shear strain between the affected and unaffected sides, we calculated the shear strain when PMI ROI was at the farthest left of the PMA ROI for each rotation cycle. This moment will be referred to as time P for brevity. The mean shear strain and its standard deviation at time P across all five rotation cycles were calculated to compare the affected and the unaffected sides. The above data analysis was completed with MATLAB software. We ensured reproducibility by executing our algorithm multiple times, verifying that the results were consistent and repeatable across each execution.

Two videos of PMA and PMI motion during the passive rotation cycles were first recreated from the saved data from one passive rotation cycle in the volunteer’s affected or unaffected shoulder. The PMA ROI was overlaid on the US B-mode image in red, and the PMI ROI in blue The video clips were also customized to show shear strain, cumulative displacement of PMA, and PMI ROI, synchronized with the US B-mode images. The B-mode clips in these two videos show that the PMI and the PMA muscles moved less independently on the affected side compared to the unaffected side. The shear strain and displacement plots demonstrate the same trend, where a larger difference between the PMA and PMI ROI displacement, and thus a larger shear strain, was observed on the unaffected side compared with the affected side.

Figure 2 shows B-mode images at two different time points during the first rotation cycle on the unaffected side (Fig. 2 a) and the affected side (Fig. 2 b). The PMA ROI was overlaid on each B-mode image in red and PMI ROI in blue. Time 0 s represents the beginning of the rotation cycle when PMI ROI and PMA ROI were at the same lateral position. Time \(P_{n}\) and time \(P_{a}\) represent the moments when PMI ROI was farthest to the left of PMA ROI on the unaffected and affected sides, respectively. In Fig. 2 , the difference between the PMA and PMI ROI lateral displacement was larger on the unaffected side at time \(P_{n}\) (Fig. 2 a) than on the affected side at time \(P_{a}\) (Fig. 2 b).

B-mode images with PMA ROI and PMI ROI overlaid in red and blue, respectively, on a the unaffected side and b the affected side at 0 s, the beginning of the rotation cycle, and at P, when PMI ROI was at the farthest left of PMA ROI. ‘L’ denotes the left side of the transducer

Figure 3 plots the shear strain between PMI ROI and PMA ROI (left y-axis) and the mean displacement of PMI ROI and PMA ROI (right y-axis) over time in the first rotation cycle. Positive displacement represents movement to the right, and negative displacement represents movement to the left. The vertical dashed lines indicate the time points when the PMI ROI was farthest to the left of the PMA ROI (i.e., \(P_{a}\) and \(P_{n}\) in Fig. 2 ). \(P_{a}\) and \(P_{n}\) also indicate the time points when a single shear strain value was calculated on the affected and unaffected sides for comparison in this rotation cycle.

The shear strain and mean displacement of the PMA and PMI ROIs over time during the first rotation cycle on unaffected and affected sides

In Fig. 3 , the shear strain at time \(P_{a}\) on the affected side was less than the shear strain at time \(P_{n}\) on the unaffected side. The same trend was observed when calculating the mean ± standard deviation shear strain at time P across all five rotation cycles. Specifically, the mean ± standard deviation shear strain at time P across five rotation cycles on the affected side was 0.40 ± 0.09, significantly lower than the mean ± standard deviation shear strain on the unaffected side at 1.09 ± 0.18 ( p <0.05).

This case study is the first to evaluate the shear strain between the PMA and PMI muscles of the affected and the unaffected sides of a human subject with chronic shoulder pain using dynamic US imaging. Previous reports have investigated the relationship between the shear strain within the thoracolumbar fascia and lower back pain, demonstrating that thoracolumbar fascia shear strain was reduced in human subjects with lower back pain compared to those without lower back pain [ 7 ]. Our case study extends the shear strain evaluation method to the PMI and PMA muscles. In alignment with the reports in [ 7 ], our results demonstrate that the shear strain between the PMA muscle and the PMI muscle on the affected side is less than that on the unaffected side (i.e., \(0.40\pm 0.09\) vs \(1.09\pm 0.18\) ). These results suggest that shear strain between the PMA muscle and the PMI muscle may be able to serve as a biomarker to elucidate the pathophysiology of myofascial dysfunction in the shoulder and potentially aid in monitoring the progression or response to treatment in individuals with myofascial dysfunction in the shoulder. Note that our analysis was designed to compare the shear strain between the affected and the unaffected side in a single case and does not aim to infer statistical significance across a broader population.

One possible explanation for the observed reduced shear strain on the affected side is the aggregation of HA in the muscle and its fascia. In physiologic quantities, HA functions as a lubricant and as a viscoelastic shock absorber [ 18 ]. Previous work has suggested that the aggregation of HA can result in increased tissue viscosity, which may lead to the formation of the taut bands that constitute trigger points, causing dysfunctional gliding of intra- and intermuscular deep fascial planes [ 19 ]; this may result in a lower shear strain.

The sonographic features of the deep fascia include multiple hyperechoic (fibrous layers) and hypoechoic (loose connective tissue) lines parallel to each other. Differential gliding of the fibrous layers is expected in healthy muscle during movement as measured by the shear strain. In contrast, HA aggregation may lead to thickening of the deep fascia and/or adhesions between the layers of connective tissue [ 6 , 20 ], consequently reducing the shear strain.

To further validate our findings, future work will enroll more patients. In addition, the accuracy of identifying the appropriate imaging plane for evaluation may vary depending on the operator’s skills. Artificial intelligence-navigated US imaging may be investigated to aid in image plane-finding to enhance the accuracy and efficiency of the evaluation process [ 21 , 22 ]. Additional future work will include investigating the relationship among shear strain, myofascial pain, and HA aggregation, which will verify the role of shear strain as a biomarker for myofascial dysfunction and pain.

Conclusions

This case study is the first to report the shear strain between the PMA and PMI muscles in a human subject with chronic shoulder pain. The shear strain between the PMA and PMI muscles on the affected side was reduced compared to the unaffected side. Our findings are promising for using US imaging for shear strain evaluation between the PMA and PMI muscles, which may serve as a useful biomarker to elucidate the pathophysiology of myofascial dysfunction.

Availability of data and materials

The datasets used and analyzed during the current study are available from the corresponding authors upon reasonable request.

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Acknowledgements

We appreciate the help of colleagues at the Department of Physical Medicine and Rehabilitation, Johns Hopkins Medicine. We also express sincere appreciation to the volunteer patient reported in this study.

This work was funded by NIH Grant R61 AT012279.

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Jonny Huang & Preeti Raghavan

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Contributions

LZ collected data, augmented existing code, performed the analysis, and drafted the initial manuscript. JH operated the imaging equipment and acquired the data. PR initiated the study, edited the manuscript, and supervised patient management. MALB provided the initial code, demonstrated implementations, assisted with data interpretation and analyses, edited the manuscript, and co-supervised the study. All authors read and approved the final manuscript.

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Correspondence to Muyinatu A. Lediju Bell or Preeti Raghavan .

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Written informed consent was obtained from the volunteer for publication of this case report and any accompanying images.

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P.R. is co-founder of Mirrored Motion Works, Inc. The remaining authors have no competing interests.

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Zhao, L., Huang, J., Bell, M.A.L. et al. Measuring myofascial shear strain in chronic shoulder pain with ultrasound shear strain imaging: a case report. BMC Musculoskelet Disord 25 , 412 (2024). https://doi.org/10.1186/s12891-024-07514-x

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Minimizing IP issues associated with gene constructs encoding the Bt toxin - a case study

• Md Mahmudul Hassan 1 , 2 ,
• Francis Tenazas 1 ,
• Adam Williams 1 ,
• Jing-wen Chiu 3 ,
• Charles Robin 1 ,
• Derek A. Russell 4 &
• John F. Golz 1  

BMC Biotechnology volume  24 , Article number:  37 ( 2024 ) Cite this article

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Metrics details

As part of a publicly funded initiative to develop genetically engineered Brassicas (cabbage, cauliflower, and canola) expressing Bacillus thuringiensis Crystal ( Cry )-encoded insecticidal (Bt) toxin for Indian and Australian farmers, we designed several constructs that drive high-level expression of modified Cry1B and Cry1C genes (referred to as Cry1B M and Cry1C M ; with M indicating modified). The two main motivations for modifying the DNA sequences of these genes were to minimise any licensing cost associated with the commercial cultivation of transgenic crop plants expressing Cry M genes, and to remove or alter sequences that might adversely affect their activity in plants.

To assess the insecticidal efficacy of the Cry1B M / Cry1C M genes, constructs were introduced into the model Brassica Arabidopsis thaliana in which Cry1B M / Cry1C M expression was directed from either single ( S4 / S7 ) or double ( S4S4 / S7S7 ) subterranean clover stunt virus (SCSV) promoters. The resulting transgenic plants displayed a high-level of Cry1B M / Cry1C M expression. Protein accumulation for Cry1C M ranged from 5.18 to 176.88 µg Cry1C M /g dry weight of leaves. Contrary to previous work on stunt promoters, we found no correlation between the use of either single or double stunt promoters and the expression levels of Cry1B M / Cry1C M genes, with a similar range of Cry1C M transcript abundance and protein content observed from both constructs. First instar Diamondback moth ( Plutella xylostella ) larvae fed on transgenic Arabidopsis leaves expressing the Cry1B M / Cry1C M genes showed 100% mortality, with a mean leaf damage score on a scale of zero to five of 0.125 for transgenic leaves and 4.2 for wild-type leaves.

Conclusions

Our work indicates that the modified Cry1 genes are suitable for the development of insect resistant GM crops. Except for the PAT gene in the USA, our assessment of the intellectual property landscape of components presents within the constructs described here suggest that they can be used without the need for further licensing. This has the capacity to significantly reduce the cost of developing and using these Cry1 M genes in GM crop plants in the future.

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Introducing Crystal ( Cry ) genes from the soil bacteria Bacillus thuringiensis into commercially grown crop plants is a highly effective strategy to control insect pests, as insects across broad taxonomic groupings are susceptible to the encoded Bt toxins [ 1 ]. However, a common problem associated with this control strategy is the development of insect resistance to the Bt toxin present in the transgenic plants [ 2 , 3 ]. Several approaches have been used to reduce or prevent the development of insect resistance including the use of refuge crops (providing sufficiently high populations of susceptible insects to prevent resistance genes from becoming homozygous), high expression of Cry genes in plants, deploying different Cry genes in individual plants in a crop (seed mixtures), and combining multiple Cry genes (i.e., stacking) in the same plant [ 4 , 5 , 6 , 7 , 8 ]. Of these, high expression and stacking of Cry genes in the same plant are considered the most practical effective strategies [ 1 , 5 , 9 , 10 ]. For example, plants expressing both Cry1Ac and Cry1C genes greatly delayed the emergence of resistance to the encoded toxins by Diamondback moth (DBM) ( Plutella xylostella ) [ 11 ]. Plants with stacked Cry genes are also protected from insects that are less susceptible to Bt toxins such as Helicoverpa armigera [ 12 ]. For this reason, plants harbouring stacked Cry genes are favoured by companies developing Bt crops as exemplified by the replacement of GM cotton containing a single Cry ( Cry1Ac ) gene with a gene stack ( Cry1Ac / Cry2Ab ) [ 7 ]. Although plants with stacked Cry genes have been successful in controlling insect pests in the field, there is still the potential for resistance to develop. The most common form of insect resistance to a Bt toxin is associated with a mutation in the receptor that binds to the toxin in the insect mid-gut [ 13 , 14 , 15 ]. Therefore, selection of Cry genes used for stacking is an important factor determining durability of the Bt toxin in the field, as different Bt toxins may bind to different receptors with different strengths. As these binding patterns are becoming increasingly well understood, it is now possible to optimize stacking by selecting Bt genes that are not susceptible to known resistance mechanisms in particular insect targets.

High-level accumulation of Bt toxin within plant tissues is generally lethal to insects that are either fully susceptible or have a single copy of a recessive gene for resistance [ 2 , 9 , 16 , 17 ]. Cry gene expression in plants depends on many factors including their nucleotide structure, the promoter used to drive their expression, and the location and copy number of the Cry gene within a plant genome [ 18 ]. A suboptimal nucleotide structure is among the main factors contributing to low Cry gene expression in plants as, due to their bacterial origin, Cry genes contain many sequences that negatively impact on protein production in eukaryotic cells. The presence of signal sequences required for polyadenylation, mRNA decay and splicing, also affects mRNA structure and accumulation in plants [ 19 , 20 , 21 ]. For example, the presence of three AATAAA repeats within the coding region of Cry3A is associated with premature polyadenylation of the gene when expressed in plants, as these sequences match the polyadenylation signal usually found in the 3’-untranslated region of many eukaryotic genes [ 22 , 23 , 24 ]. In addition, Cry gene expression in plants is impacted by differences in nucleotide content between bacterial and eukaryotic genomes. For instance, Cry genes have a higher AT content (65%) compared to typical dicot (55%) or monocot (45%) plant genes [ 18 ]. These differences mean that the Cry genes utilize codons that are less common in plants, which reduces the rate of protein production due to the limited size of tRNA pools for these codons [ 25 ]. Furthermore, if a ribosome fails to incorporate the corresponding tRNA for a rare codon, translation may be aborted, resulting in the ribosome becoming disassociated from the mRNA. Poorly translated mRNAs are prone to degradation in the host cell by nonsense mediated RNA decay [ 20 ]. Rectifying these issues, together with the removal of spurious polyadenylation signal sequences and sequences that might be responsible for mRNA instability, such as the ATTTA motif, from plant-expressed Cry genes can significantly improve production of the encoded Bt toxin in plants [ 21 , 26 , 27 , 28 , 29 ]. By changing the composition of codons so that they better reflect the distribution of those seen in typical plant genes, significant increases in Bt protein have been observed in transgenic tobacco, tomato and potato plants [ 21 ].

Commercialization of GM crops requires the developer to manage multiple patent right hurdles, due to the complex patent landscape associated with the technologies used in the creation of GM crops. Almost all the significant components of the constructs used in plant transformation are patented. These include the ‘effect gene’ and associated regulatory sequences, as well as the selectable marker [ 30 ]. For example, use of an antibiotic resistance gene as selectable marker in plant transformation is restricted by a patent owned by Monsanto, however, this IP right only applies in the USA. Another example of a patent that has a considerable impact on construct design is the use of the cauliflower mosaic virus (CaMV) 35 S promoter to drive selectable marker gene activity in plants [ 30 ]. Patent holders frequently do not allow access to a patented technology if they are themselves using it commercially or have sole licensing agreements with other entities, and where they do allow it, licensing costs can be considerable. Therefore, at early stages of GM crop development, Freedom to Operate (FTO) needs to be established for technologies used in introducing new traits to crops of interest. Without securing all the necessary legal rights, GM crop developers may be exposed to legal liabilities, which ultimately prevent the use of the developed crop. A notable example of the complexity associated with IP issue was the development of golden rice, a transgenic rice line rich in ß-carotene (a precursor of vitamin A). Delivery of the golden rice for public use has been delayed, in part due to extensive patenting issues, associated with 72 patents owned by 40 organization [ 30 , 31 ].

As a part of Australian-Indian government strategic initiative, our aim was to develop Bt-expressing Brassica crops for commercial use in both countries where the licensing costs associated with the use of this technology was minimized. Here, we describe the generation of a Cry1B M / Cry1C M gene stack that may be used as an effective insecticide when introduced into plants. Nucleotide modification of the Cry1B / Cry1C genes, together with careful selection of components used in the design of the constructs, ensured both high-level expression in plants and minimal licensing costs associated with the use of these constructs. We demonstrate under laboratory conditions that Arabidopsis plants expressing the modified Cry genes display high-level resistance to diamondback moth (DBM) larvae, consistent with our modifications not adversely affecting the lethality of the Cry genes. The results of this study provide an example of how new Bt-expressing constructs that are relatively free of third-party IP may be generated, particularly for deployment in developing nations where farmers may have limited capacity to pay costs associated with Bt crops developed by multinational seed companies.

Plant materials and growth condition

The Columbia-0 ecotype of Arabidopsis thaliana was used as wildtype in this study. Seeds were either grown on a soil/perlite mix or plated on half-strength Murashige and Skoog (½ MS) media containing Phytagel. Seeds were stratified at 4°C for 2–3 days prior to placement in a growth room under continuous light at 18–20°C or a growth cabinet under continuous light at 20–22 °C.

Modification of Cry1B/Cry1C sequences

The DNA sequences of the original Cry1B / Cry1C genes were modified using the DNA strider software [ 32 ]. Initially, codon use frequency of the Cry gene was determined using the Sequence Manipulation Suite ( www.bioinformatics.org/sms2/codon_usage.html ) and then systematically replaced with synonymous codons to better reflect the codon usage of endogenous Brassica genes [ 33 ] (Supplementary Figs.  1 and 2 , Supplementary Tables 1 and 2 ). ORFfinder ( https://www.ncbi.nlm.nih.gov/orffinder/ ) was then used to determine the position of ORFs in the six reading frames of the Cry1B M /Cry1C M genes. ORFs that were 75 amino acids or longer were disrupted through the introduction of a stop codon (Supplementary Table 3 ). In addition, sequences that may function as splice sites (AGGT) [ 34 ] and the ATTTA instability motif [ 18 ] were altered by changing nucleotides within these motifs (Supplementary Figs.  1 and 2 ).

Selection of components for Cry1B M /Cry1C M constructs

The Cry1B M construct was designed to have either one or two S4 subterranean clover stunt virus (SCSV) promoters [ 35 ] upstream and the pea RUBISCO E9 terminator [ 36 ] downstream of the Cry coding sequence. In contrast, either one or two SCSV S7 promoters [ 35 ] were placed upstream and the Flaveria bidentis MALIC ENZYME ( ME ) terminator [ 35 ] downstream of the Cry1C M gene (Fig.  1 ). Our previous work with Cry1B/Cry1C genes identified leaky expression of Cry1C in E. coli . To prevent this, an intron from potato ST-LS1 gene [ 37 ] was placed within the Cry1C M coding sequence. A DNA fragment containing these elements ( ME ter : Cry1C M -intron::S7S7-S4S4::Cry1B M :: E9 ter ) was then synthesized to our specifications by Biomatik ( www.biomatik.com ) and cloned in the Eco RI/ Hin dIII sites of the pUC19 vector. This vector was subsequently digested with Bgl II enzyme to remove one copy of the S4 and S7 promoters resulting in single stunt promoter constructs ( ME ter Cry1C M -intron::S7-S4::Cry1B M :: E9 ter ) . Cry1 M genes under single or double stunt promoters were then isolated as Pac I fragments from their respective vectors, and cloned into binary vector PIPRA560 [ 36 ].

A NPTII expression cassette comprising a figwort mosaic virus 34 S promoter [ 38 ], the coding sequence of the NEOMYCIN PHOSPHOTRANSFERASE II ( NPTII ) gene [ 39 ] and the terminator of Agrobacterium MANNOPINE SYNTHASE ( MAS ) gene ( MAS ter ) [ 36 ] was synthesized and cloned into the Eco RI/ Hin dIII sites of the pUC19 vector. Included in this synthetic cassette were flanking tandemly arranged Lox sites to enable removal of the selectable marker cassette from the T-DNA as part of a strategy to generate marker-free plant transgenic plants (e.g [ 40 ]). . A glufosinate-ammonium resistant selectable marker was generated by replacing NPTII with the PHOSPHINOTHRICIN ACETYLTRANSFERASE ( PAT ) gene [ 41 ]. The PAT selection cassette was then isolated from this plasmid and cloned into the Sac II site of the binary vectors containing the modified Cry genes under the control of either S7-S4 or S7S7-S4S4 stunt promoters. These constructs, pJG1024 (single stunt (SS) construct) and pJG1027 (double stunt (DS) construct) (Fig.  1 ) were then introduced into Agrobacterium (C58) via electroporation.

Schematic diagram of T-DNA region of constructs used to test the insecticidal activity of Cry1B M and Cry1C M genes in plants; 34S pro : Promoter of Figwort mosaic virus (FMV) 34S RNA gene [ 38 ]; MAS ter : Agrobacterium tumefaciens MANNOPINE SYNTHASE ( MAS ) gene terminator [ 36 ]; Cry1B M / Cry1C M : Modified Cry1B / Cry1C genes; S4 / S7 : Subterranean clover stunt virus S4 and S7 promoters [ 35 ]; E9 ter : Terminator region of the pea Rubisco E9 gene [ 36 ]; ME ter : Terminator region of Flaveria bidentis MALIC ENZYME ( ME ) gene [ 35 ]; Intron: second intron ( IV2 ) of the potato gene ST-LS1 [ 37 ], E1 leader: 5’ leader sequence of the tapetum specific E1 gene of Oryza sativa, Lox sites: tandemly arranged Lox P sites; LB: Left border of the PIPRA560 plant binary vector; RB: Right border of the PIPRA560 plant binary vector

Plant transformation

pJG1024 and pJG1027 were inserted into wild-type Arabidopsis thaliana using floral dipping [ 42 ]. Transgenic plants were identified using glufosinate-ammonium (100 µg/ml) selection on soil and further confirmed by amplifying the herbicide resistance gene PAT using primers BaR-F (5’-GTTGGTTGCTGAGGTTGAG-3’) and BaR-3′R (5’-TGGGTAACTGGCCTAACTGG-3’). For each construct, ten independently transformed T 1 lines were randomly selected, and their progeny exposed to glufosinate-ammonium selection. Based on segregation ratios, lines judged to have a single T-DNA insertion (1:3, Glufosinate ammonium sensitive: Glufosinate ammonium resistant) were selected for further analysis. Homozygous T 2 plants derived from T 1 lines identified as having a single segregating T-DNA insertion were used in all subsequent assays.

Insect bioassay

A colony of diamondback moth (DBM) susceptible to the Bt toxins encoded by Cry1 M genes were maintained in an insect growth chamber at 25 °C. Arabidopsis plants homozygous for the T-DNA insertion were grown for ~ four weeks and their mature leaves collected for insect bioassay, RNA extractions, and protein quantification. For insect bioassay, two leaves were placed on a moist filter paper in a plastic cup (size 40 × 50 mm). On each leaf, ten DBM larvae (1st instar) were deposited. Larval mortality and leaf damage were scored after 48 h and again at 72 h if the larvae had survived after 48 h. Insect bioassays were performed at 25 °C. Leaf damage was scored on scale from 0 (no visible damage) to 5 (leaf skeletonised).

Quantification of Cry1C M protein

The abundance of Cry1C M protein in leaves of transgenic plants was quantified using a Cry1C-specific enzyme-linked immunosorbent assay (ELISA) assay (Cry1C-specific Quantiplate Kit; Envirologix, USA). Briefly, leaves collected from transgenic lines were weighed and put into a 1.5 ml tube. The tubes were then placed in Ziplock plastic bags containing silica beads and dried over a period of two weeks. Protein was extracted from 1 mg dried tissue using the extraction buffer supplied with the kit. The ELISA was performed according to the manufacture’s instruction. The amount of expressed Cry1C M protein in the leaf sample was calculated from a standard curve generated using the pure Cry1C protein supplied with the Quantiplate ELISA kit. The amount of Cry1C M protein content in the samples was determined using the standard curve and given as µg per gram dry weight (DW) of leaves.

RNA extraction and reverse transcription quantitative PCR (RT-qPCR)

RNA was extracted from leaf tissue using a Spectrum Plant Total RNA kit (Sigma, USA) according to the manufacturer’s protocol. Extracted RNA was treated using Turbo DNA-free kit (Ambion, USA) to remove contaminating genomic DNA before first strand cDNA was generated using Oligo (dT) primers and Superscript III reverse transcriptase (Thermo Fisher). RT-qPCR was performed using a SensiMix SYBR No-ROX Kit (Meridian, Australia). Briefly, 10 µl qPCR reactions containing 1 µl diluted (1:10) cDNA, 2.5 µM forward and reverse primer, with 1x SYBR Green Master Mix were set up in triplicate and run on a Bio-Rad CFX96 real time PCR machine. Cycle threshold (Ct) values were calculated using the Bio-Rad CFX manager version 3.1. The relative Cry1B M /Cry1C M mRNA expression level were determined using the comparative Ct method and normalized to ACTIN2 ( AT3G18780 ). The sequences of RT-qPCR primer used in this study were, Actin2-F (5’-TCTTCCGCTCTTTCTTTCCA-3’), Actin2-R (5’-TCTTCCGCTCTTTCTTTCCA-3’), Cry1B-F (5’-TAGAGGGACCGCTAACTATT C-3’)/Cry1B-R (5’-CGACAACCGATGTGAGTAAG-3’), and Cry1C-F (5’-GAAAGAATGCCGCAA TGTC-3’)/ Cry1C-R (5’-CTTACAACCGTGGGCTTAAC-3’).

IP landscape analysis

IP searches were performed using keywords and sequence-based approaches to identify relevant patent filings in national databases in the US ( https://ppubs.uspto.gov/pubwebapp/static/pages/ppu bsbasic.html), Australia ( https://www.ipaustralia.gov.au/ ), EPO ( https://www.epo.org/en/searching-for-patents/technical/espacenet ), WIPO ( https://patentscope.wipo.int/search/en/search.jsf ), and India ( https://iprsearch.ipindia.gov.in/publicsearch ). This provided information about the legal status of patents as well as their file histories. Results from these searches are provided in Table  2 and Supplementary Table 4 .

Modification of Cry 1B and Cry1C genes used in this study

To maximize activity of Cry1B / Cry1C genes in plants, we synthesized modified Cry1 sequences ( Cry1 M ) to eliminated features that are known to reduce the expression of these genes in eukaryotic cells. This included extensive codon-optimization, which involved the selection of codons used at high frequently in Brassica genes and are GC-rich (Supplementary Tables 1  and 2 ) [ 33 ]. Following this, the GC-content of the modified Cry genes Cry1B M and Cry1C M was 47.7% and 45%, respectively, which is higher than in their unmodified versions (Table  1 ).

Alternative open reading frames greater than 75 amino acids in the modified Cry genes were disrupt through the placement of a stop codon within the ORF (Supplementary Table 3 ), a key requirement for GM plants needing regulatory approval before commercialisation. Sequences known to affect transcript stability, such as ATTTA [ 18 ] and potential splice site AGGT [ 34 ], were removed from the modified Cry gene sequences along with any internal polyadenylation signal sequences that might cause premature termination of transcription (Supplementary Figs.  1 and 2 ). Following these modifications, the degree of identify between known Cry1B genes (e.g., Cry1B1 and Cry1B2) and Cry1B M was 79% at DNA level (Table  1 ) and the identity between Cry1C M and four other Cry1C genes ranged from 75 to 81% (Table  1 ). To the best of our knowledge this reduced DNA sequence identity means that Cry1B M and Cry1C M do not infringe IP associated with the original Cry1B and Cry1C sequences (Supplementary Table 4 ).

Design of Cry1B M / Cry1C M constructs

Where possible components and methodologies that are free of third-party IP were used in the development of the Cry1 M constructs to minimize IP obstacles, including any licensing costs associated with eventual commercial cultivation of plants expressing the Cry1 M genes. We performed a detailed online database search of the patents surrounding the binary vector, promoters, terminators, selectable markers, Cry genes and methodologies used in the generation of the Bt constructs and list their current IP status in Australia, USA, and India in Table  2 and Supplementary Table 4 .

The Cry1B M / Cry1C M gene construct was designed so that physical linkage between the genes ensured that they integrate into the same chromosomal site following transformation (Fig.  1 ). This design eliminated the need for crossing to combine transgenes following their separate introduction into plants. Binary vector PIPRA560 was selected for use in these experiments as the tangible property right was available under licence-free terms for commercial cultivation in developing countries and under modest fee-based terms for developed countries [ 36 ]. The herbicide resistance gene PAT was chosen as a plant selectable marker for transgenic plant selection as it had FTO in both Australia and India. The FMV 34 S promoter [ 38 ] and the terminator region of the MAS [ 36 ] gene were placed upstream and downstream of the PAT gene, respectively. These components are present within the PIPRA560 plasmid and were obtained under a UC Davis licensing agreement. Subterranean clover stunt virus (SCSV) promoters S4 and S7 were selected because previous work had shown that their use with other Cry genes led to high-level expression and subsequent insecticidal activity [ 35 ]. These are now available free of third-party IP (see Table  2 ). Two different configurations of these promoters were tested; the first being single S4 / S7 promoters (Fig.  1 A; hereafter referred to as SS) and the second being a double promoter configuration (Fig.  1 B; hereafter referred to as DS). By analysing expression of the Cry1 M genes arising from SS and DS constructs, we addressed whether these promoters arranged in tandem conferred a significantly higher level of expression than a single promoter configuration, as suggested in previous studies of these promoters [ 35 ].

Generation of transgenic lines and insect bioassay

More than 40 independent T 1 plants transformed with a T-DNA containing either the SS cassette or a DS cassette were generated. Of these, ten SS and DS primary transformants were randomly selected for initial insect bioassays and Cry1C protein content analysis (data not shown). First instar DBM larvae were placed on leaves collected from these primary transgenic Arabidopsis lines hemizygous for the T-DNA, along with those from wild-type plants. Larvae fed on the wild-type leaves developed normally, resulting in severe leaf damage associated with unconstrained feeding (Fig.  2 A). In contrast, transgenic leaves remained undamaged from larval feeding (Fig.  2 A). The number of live and dead larvae were assessed (Table  3 ).

Insect bioassay on Arabidopsis leaves derived from transgenic plants homozygous for Cry1B M / Cry1C M transgene. ( A ) Transgenic leaves expressing Cry1B M / Cry1C M genes under a single stunt (SS) and double stunt (DS) S4 and S7 promoters. ( B ) Image showing insect larval guts (indicated with blue arrowhead) after feeding on wild-type leaves. ( C ) Insect mortality found in individual transgenic lines having Cry1B M / Cry1C M expression under a single stunt ( S4 / S7 ) promoter. ( D ) Insect mortality associated with in individual transgenic lines with Cry1B M / Cry1C M expression under the control of double stunt ( S4S4 / S7S7 ) promoters

After 24 h, approx. 99% larvae placed on the T 1 leaves were dead, whereas all larvae placed on the wild-type leaves were alive and actively feeding (Table  3 ). After 48 h, all remaining larvae feeding on the transgenic leaves were dead, while almost all the larvae feeding on the wildtype leaves were alive (Table  3 ). Significant larval death (31.5%) was seen on the wildtype leaves, but only after day 6. Moreover, ~ 40% larvae placed on the wild-type leaves were found to have moulted beyond 1st instar, which was not observed for larvae placed on transgenic leaves. During the insect bioassay, the health of the larvae was examined. Healthy larvae were present on the wild-type leaves, whereas those feeding on the transgenic leaves appeared shrivelled and small, including some displaying gut bursting (Fig.  2 B). Segregation analysis performed on each of these ten primary transformants identified six SS transformants and six DS transformants with a single segregating T-DNA insertion. Homozygous T 3 progeny derived from these lines were subsequently used for insect feeding assays, which revealed close to 100% mortality within 48 h of feeding on transgenic leaves (Fig.  2 C, D). Interestingly, there was no discernible difference in insect mortality between transgenic leaves expressing Cry1 M genes under a single stunt promoter from those under a double stunt promoter (Fig.  2 C, D).

Cry1B M and Cry1C M expression level in the plants

Expression of Cry1B M and Cry1C M in vegetative tissue of seedlings homozygous for the SS and DS constructs was measured by RT-qPCR. While this revealed expression of both transgenes in all plants (Fig.  3 A, B), considerable variation was observed. For instance, lines SS-08 and DS-08, displayed high levels of both Cry1B M and Cry1C M expression, whereas low expression of both genes was detected in lines DS-13 and DS-14 (Fig.  3 A, B). Except for SS-08, SS-09, DS-08 and DS-17, most transgenic lines ( n  = 12) displayed significant differences between the Cry1B M and Cry1C M expression with the majority having higher Cry1B M expression compared to Cry1C M (Fig.  3 A, B).

Expression of Cry1B M and Cry1C M transgenes in the transgenic Arabidopsis plants. ( A ) Cry1B M / Cry1C M expression seen in transgenic lines with a single stunt ( S4 / S7 ) promoter (six independent transgenic events with single copy T-DNA with 5 plants per event). ( B ) Cry1B M / Cry1C M expression in transgenic lines with double stunt ( S4S4 / S7S7 ) promoters (six independent transgenic events examined with 5 plants per event). ( C ) Comparison of Cry1B M and Cry1C M expression (average of six independent single copy T-DNA transgenic events with 5 plants per event) under S4 / S7 single and double stunt promoters. An unpaired t -test found no statistical differences in the range of Cry gene expression values seen in plants with single or double stunt promoters. ( D ) Comparison of Cry1C M protein content in plants with single or double stunt promoters as assessed by enzyme-linked immunoabsorbent assay (ELISA) ( n  = 3 progeny plants derived from each of the six lines). SS: Lines with single stunt promoters, DS: Lines with double stunt promoters. Lines denoted by “*” indicates expression of Cry1B M and Cry1C M is significantly different. Statistical significance was assessed by Mann-Whitney test [ 44 ]

Levels of Cry protein were quantified by ELISA (Table  4 ). This analysis was restricted to Cry1C M due to the unavailability of a Cry1B M -specific ELISA kit. For SS lines, the quantity of Cry1C M protein ranged from 8.18 to 176.88 µg/g leaf dry weight (DW) with significant differences in protein content between transgenic lines (F = 87.20, p  < 0.0001).

Similarly, Cry1C M protein in DD lines ranged from 5.18 to 134.75 µg/g leaf DW with significant differences also detected between lines (F = 97.29, p  < 0.0001). It is worth noting that a previous study using a leaf-dip assay with pure Cry1Ca4 protein found that the lethal concentration (LC 50 ) to be < 1.18 ppm when fed to 26 global DBM populations and an average of only 0.18ppm in Indian DBM populations [ 45 ]. This suggests that most of transgenic lines generated in this study had Cry1C protein levels that would by themselves be effective against DBM (Table  4 ; Fig.  3 D).

Initial observations failed to detect a noticeable difference in the range of insecticidal activity displayed by transgenic lines expressing Cry1B M / Cry1C M under the control of single or double stunt promoters (Fig.  2 C, D). Consistent with this observation, no significant differences were found in the expression of lines transformed with SS as opposed to DS constructs as measured by RT-qPCR of the modified Cry genes ( Cry1B M , p-value = 0.161; Cry1C M , p-value = 0.112). Similarly, the range in Cry1C M protein content in leaves of SS and DS lines did not differ significantly (p-value 0.191).

Correlation between the Cry1C M expression and protein content

To determine the relationship between the amount of Cry1C M mRNA and corresponding protein content, RT-qPCR and ELISA results were compared. In most cases, levels of mRNA corresponded closely to protein content (SS-08, SS-09, DS-14, DS-17; Fig.  4 A). Furthermore, a Spearman rank correlation coefficient test identified a strong statistical correlation between the Cry1C M protein content and Cry1C M transgene expression (R s =0.846, P  = 0.0013). While there was a good correlation between gene expression and protein levels, there were some notable exceptions. For instance, the highest amount of Cry1C M transcript was detected in line DS-08 but this did not correlate with the highest amount of detectable Cry1C protein. Conversely, the high level of Cry1C protein content in line SS-08 arose from transcript levels of Cry1C M that were nearly half of that observed in DS-08 (Fig.  4 A).

Comparison of Cry1C M transgene expression and protein accumulation in transgenic Arabidopsis lines. ( A ) Histogram showing the amount of Cry1C M mRNA and protein content in twelve transgenic lines tested. ( B ) Graph showing the relative transgene expression and Cry1C M protein content in the lines listed in Fig.  2 C and D. Results from a Spearman rank correlation test are shown. SS: Lines with single stunt S4 / S7 promoters; DS: Lines with double stunt S4S4 / S7S7 promoters

The Cry1B / Cry1C combination, whose modification is described here, was previously shown to be effective against DBM [ 43 , 44 ] but has never been used in commercially available GM crops or as the basis for sprayable Bt insecticides [ 46 , 47 ]. For instance, purified Cry1Ba2 and Cry1Ca4 proteins displayed LC 50 values < 0.91 ppm and < 1.18 ppm, respectively, when tested against of DBM populations [ 45 ]. Furthermore, no cross-resistance was found between Cry1Ba2 and Cry1Ca4, or in experiments aimed at generating resistance to the two Bts in DBM laboratory [ 46 ]. The minor resistances that were observed in these studies were unstable and genetically recessive, as well as being associated with a high fitness costs [ 46 ]. Where resistance to Cry1C in DBM has been identified, it manifests as a polygenic trait [ 48 ]. Taking these observation together with the fact that Cry1B and Cry1C bind to different receptors in the insect gut [ 47 ]. This suggests that insect resistance to this combination of Cry genes is unlikely to arise.

While previous work [ 46 , 47 ] found that transgenic Brassica expressing the Cry1B / Cry1C stack displayed robust resistance to a range of lepidopteran pest species in small trials run in India, these lines (developed by a public/private-funded consortium), were not developed further due to the length of time likely to be required to gain regulatory approval for commercial planting. Despite this set-back, the Australian and Indian public partners in the public/private consortium wanted to continue the development of Brassica expressing Bt toxins for their respective markets. To facilitate this, it was necessary to alter the sequence of the Cry genes so that they were unequivocally not that of the private partner. We used this opportunity to both free the new Cry1 M gene constructs of proprietary IP as far as practicable and to optimise the nucleotide structure of the Cry genes for expression in plants. The PIPRA560 plant binary vector was used to deliver the Cry constructs to plants. The tangible property right holder, the University of California, Davis, allowed licence free research use and free commercialisation use for developing countries, including India. The MTA terms of use state that any construct developed using PIPRA560 must also be free to use by others.

As stated previously, one way to overcome the development of resistance to Bt toxin is to express the Cry gene at high level so that insects heterozygous for resistance mutation are eliminated from the population. Given this, we chose to test double stunt SCSV promoters for our Bt toxin gene construct design as plants expressing Cry gene under two stunt promoters would be more effective in killing insect than their single stunt counterpart. The results reported here showed no obvious difference in insect mortality between the plants expressing Cry1 M genes under single or double stunt SCSV promoters (Fig.  2 C, D; Table  3 ). Previous work characterising double stunt promoters had indicated that the S7S7 double promoter was better than S4S4 promoter [ 35 ], whereas our results indicate that S4S4 is slightly more effective than the S7S7 promoter (Fig.  3 C). Differences between our study and earlier work might reflect the assay system used to compare the promoter strength. For instance, the earlier studies of the S4S4 and S7S7 promoters relied upon Cry1Ab protein content assays to measure activity of the promoters, whereas in our study we used a combination of both protein and mRNA assays. As mentioned above protein production from mRNA is affected by multiple factors and hence protein content in GM plants may not be a reliable indicator of promoter strength. As performance of S4S4 and S7S7 double stunt promoters also varied according to the plant species used for transformation (cotton, tobacco and tomato; [ 35 ]), variation in SCSV promoter activity observed in our study might also reflect background differences between Arabidopsis and the plants used in earlier studies.

Despite variation in Cry1B M and Cry1C M expression between and within lines, there was no detectable variation in insecticidal activity, as close to 100% insect mortality was achieved within 48 h even in lines with low Cry1B M / Cry1C M expression (Fig.  1 B, C). Although transcript levels were measured both for Cry1B M and Cry1C M , quantification of Cry1B protein could not be performed due to lack of a Cry1B - specific ELISA commercial kit. Unfortunately, lack of access to the Cry gene constructs used in the preceding public/private partnership programme prevented us from directly testing whether the modified Cry gene sequences represent a significant improvement over the insecticidal activity of the unmodified Cry genes. Despite this, it seems reasonable to conclude that both proteins retained insecticidal activity under lab conditions. This is inferred from the observation that in some lines, one Cry gene was expressed at much higher levels than the other (e.g., SS-05, SS-16 DS-03; Fig.  3 B), yet still conferred 100% DBM larvae mortality. While there was a clear correlation between Cry1C M gene expression and protein abundance (Fig.  4 ), there were a few notable exceptions, e.g., line DS-03 and DS-08. This discrepancy presumably reflects inefficient conversion of mRNA to protein, an observation that has been reported in several other studies of Cry transgene activity [ 49 , 50 ]. However, due to the relatively modest sample size ( n  =–12 lines) in our study, as well as those reported by others [ 49 , 50 ], it is difficult to characterize a clear relationship between Cry gene expression and protein accumulation.

A potential problem arising from gene stacks is that when more than one gene is placed in the same T-DNA, their expression may be compromised due to gene silencing, particularly if they share similar sequences and regulatory elements such as promoters, 5′-UTRs and 3′-UTRs [ 51 ]. Therefore, expression analysis of each gene in plants is important, as silencing or sub-optimal expression of one gene may result in reduced efficacy of the insecticidal protection provided by the Cry gene stack. We found substantial differences in expression levels of Cry1B M and Cry1C M in most of the lines (Fig.  3 A, B). The variation in Cry1B M / Cry1C M expression seen in the same line (e.g., SS-09 & SS-10) might be a consequence of the stunt promoter arrangement. In both constructs these promoters are adjacent to one another in a reverse orientation, which may make their associated transgenes prone to gene silencing [ 52 , 53 ]. Alternatively, differences in Cry gene expression might be influenced by the Cry1B M / Cry1C M sequences, structural properties of promoters and position effects, in which genomic regions adjacent to the T-DNA insertion site influence transcription activity of the transgenes [ 51 , 54 , 55 , 56 ]. Similarly, variation in the extent of T-DNA insertion or its rearrangement prior to or after integration into the genome may influence Cry gene activity. Such variation between lines transformed with the same construct has been previously reported [ 57 ] and thus is not without precedent. Importantly, variations in Cry1B M and Cry1C M expression level observed in the transgenic Arabidopsis lines do not seemingly reflect an issue with their coding sequences. This can be inferred from the fact that in some cases Cry1B M is expressed at higher levels than Cry1C M (e.g., SS-18, DS-11), and vice versa (e.g., SS-09, DS-03).

The results provided here illustrate the types of sequence modification that can be successfully introduced into Cry genes as well as the suitability of components chosen for constructs that have FTO. The components used in the gene constructs reported here are to the best of our knowledge currently free of third-party IP in Australia and India. Confirmation that this applies in other countries would require detailed patent searches to be undertaken and legal advice sort. The use of components that have FTO in both the research and the commercialisation phases in public GM breeding programs is important as it can substantially reduce the complexities and costs faced in the commercialisation phase [ 36 ]. Proprietary elements used in the development phase, even no longer present in the sequence to be commercialised, can derail the success of the projects. While the work here only reports the activity of the Cry1B M / Cry1C M gene stack in the model plant Arabidopsis under laboratory conditions, work was undertaken to introduce these constructs into elite Brassica crop lines, and preliminary analysis suggests that they are as effective in crop plants as they are in Arabidopsis [ 58 ]. Unfortunately, funding constrains prevented these transgenic crop lines from being fully assessed for insect resistance in field trials.

Despite the obvious benefits of transgenic plants expressing Cry genes, which include preventing large scale crop losses from insect attack, this technology has been applied to only a few crops such as cotton, canola and maize which are grown on a large enough scale to make the costs of deregulation and the separation of the product in harvesting, storing and marketing economically attractive [ 59 ]. The timelines, costs, and political opposition to GM crops in a significant proportion of markets has delayed the introduction of Cry transgenes into other crops such as vegetables and major grain crops such as rice or wheat. Uptake of Bt technology in developing nations has been significantly curtailed by the difficulties of access to IP held by entities such as multinational seed companies [ 60 ]. Given this, publicly funded research organizations and academic institutions in developing nations have an incentive to develop their own Bt crops [ 36 ] in which licensing issues associated with the use of genetically modified material is minimised so that farmers can take advantage of the considerable benefits arising from the technology [ 59 ]. Our work here provides an example of an approach that might be taken to achieve this aim.

Data availability

All data generated or analyzed during this study are included in this published article and its supplementary information files. The sequences of gene constructs pJG1024 and pJG1027 has been deposited in NCBI gene bank and can be retrieved using their accession IDs which are PP194761 (pJG1024) and PP194762 (pJG1027).

Abbreviations

Crystal gene

• Bacillus thuringiensis

Arabidopsis thaliana

Subterranean Clover stunt virus

Freedom to operate

Intellectual property

Enzyme-linked immunosorbent assay

Untranslated region

Left/right border of T-DNA

Diamond back moth

Quantitative reverse transcription-polymerase chain reaction

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Acknowledgements

The PIPRA560 vector was obtained from PIPRA, Department of Plant Sciences, University of California, Davis, CA95616.

This work at the University of Melbourne was supported by the Australia/India Strategic Research Fund – Grand Challenge Project GCF010009 – Crop Plants which remove their own major biotic constraints.

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Md Mahmudul Hassan, Francis Tenazas, Adam Williams, Charles Robin & John F. Golz

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Jing-wen Chiu

Melbourne Veterinary School, University of Melbourne, Parkville, VIC, 3010, Australia

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MMH, DAR, CR and JG conceived the idea. MMH and AW undertook the molecular biology and plant work; FT and DAR conducted the insect experiments. JC and DAR conducted the IP analysis. MMH led the writing and revision of the manuscript. All authors accepted the final version of the manuscript.

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Hassan, M.M., Tenazas, F., Williams, A. et al. Minimizing IP issues associated with gene constructs encoding the Bt toxin - a case study. BMC Biotechnol 24 , 37 (2024). https://doi.org/10.1186/s12896-024-00864-3

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DOI : https://doi.org/10.1186/s12896-024-00864-3

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