anecdotal and case study evidence are good sources of

Science-Based Medicine

Exploring issues and controversies in the relationship between science and medicine

The Role of Anecdotes in Science-Based Medicine

While attending a lecture by a naturopath at my institution I had the opportunity to ask the following question: given the extreme scientific implausibility of homeopathy, and the overall negative clinical evidence, why do you continue to prescribe homeopathic remedies? The answer, as much as my question, exposed a core difference between scientific and sectarian health care providers. She said, “Because I have seen it work in my practice.”

There it is. She and many other practitioners of dubious modalities are compelled by anecdotal experience while I am not.

An anecdote is a story – in the context of medicine it often relates to an individual’s experience with their disease or symptoms and their efforts to treat it. People generally find anecdotes highly compelling, while scientists are deeply suspicious of anecdotes. We are fond of saying that the plural of anecdote is anecdotes, not data. Why is this?

Humans are social storytelling animals – we instinctively learn by the experience of others. My friend ate that plant with the bright red berries and then became very ill – lesson: don’t eat from that plant. This is a type of heuristic, a mental shortcut that humans evolved in order to make quick and mostly accurate judgments about their environment. From an evolutionary point of view it is probably statistically advantageous just to avoid the plant with the red berries rather than conduct blinded experiments to see if it really was the plant that made your friend sick.

Further, the most compelling stories are our own. When we believe we have experienced something directly, it is difficult to impossible to convince us otherwise. It’s just the way humans are hardwired.

Understanding the world through stories was a good strategy in the environment of our evolutionary history but is far too flawed to deal with the complex world we live in today. In fact, the discipline of science developed as a tool to go beyond the efficient but flawed techniques we evolved. Perhaps, for example, your friend became ill because of the raw eggs he consumed earlier in the day, and the plant had nothing to do with it. Evolutionary pressures favored a more simplistic approach to nature, one that tended to assume that apparent patterns were real.

In today’s modern society we are confronted with a dizzying array of apparent patterns and using the simple rules of thumb we evolved to deal with them is not adequate. Whether or not a treatment works for a symptom or disease is a good example. Symptoms tend to vary over time, some may spontaneously remit, and our perceptions of symptoms are susceptible to a host of psychological factors. There are also numerous biological factors that may have an effect. If we are to make reliable decisions about the effects of specific interventions on symptoms and diseases we will need to do better than uncontrolled observation, or anecdotes.

The primary weakness of anecdotes as evidence is that they are not controlled. This opens them up to many hidden variables that could potentially affect the results. We therefore cannot make any reliable assumptions about which variable (for example a specific treatment) was responsible for any apparent improvement.

Here are some specific factors that make it difficult to impossible to reliably interpret anecdotal medical evidence:

Regression to the mean: This is a statistical phenomenon whereby any extreme variation is likely to be followed by a more average variation – by chance alone. Many diseases have variable or fluctuating symptoms – good days and bad days, or periods of exacerbation followed by periods of relative relief. If a person seeks out a treatment when their symptoms are severe, by chance alone this is likely to be followed by a period when the symptoms are not as severe.

Most illnesses are self-limiting: The old saying goes that if you don’t treat a cold it will last for seven days, and if you treat it it will last for a week. Most ailments get better or improve on their own, therefore most treatments will be followed by symptom resolution even if the treatment has no biological effect. More broadly, all illnesses have a natural history, a course they typically follow over time. In order to know if a treatment is affecting that course it has to be compared to patients who are not treated, or receive a different treatment.

Multiple treatments: Often people will try multiple treatments for a disease or ailment making it impossible to tell which treatment had a beneficial effect, if any. Multiple treatments may be taken all at once, or sequentially. For example, a person with a long term illness (but one destined to have a period of relative relief) tries treatment A without effect, then treatment B without effect, then treatment C which is followed by improvements in their symptoms. They then credit treatment C, recounting how multiple other treatments had failed. However, since the person was trying some new treatment most of the time at any point that their symptoms improved there would be a treatment they could credit with that improvement.

Dead men tell no tales (the problem of reporting bias): Cancer survivor groups do not contain people who died of their cancer. Those who die of a disease are not around to give their anecdotes. There is therefore a built in reporting bias. Also, those who feel they were helped by a treatment are much more likely to boast about it than those for whom there was no apparent benefit. People like to tell the tale of the miracle cure they found and had faith in, despite the skeptics and naysayers – but their vision paid off as the treatment worked for them. People have no motivation to recount their experience with the novel treatment that did not work. Further, patients who feel they are being helped by their doctor or practitioner are more likely to return. Those who feel the treatments are not working may not come back at all to report the treatment failure.

Confirmation bias: It is a well-described psychological phenomenon that we tend to seek out and remember information that confirmed what we already believe, or want to believe, and we avoid, forget, or explain away disconfirming evidence.

Vague outcome measures: Good clinical trials use objective outcome measures – those that are binary (like death or survival), quantitative (like a blood level), or are based upon a specific physical finding. Subjective symptoms do not make good outcome measures because they require that judgments be made, and that introduces yet another variable. Should you count those mild sniffles as having a cold? If you are taking a remedy that you think will help you avoid colds you may dismiss those sniffles and report (and even remember) that you did not get any colds while taking the treatment.

The Placebo Effect: The placebo effect is actually a host of many effects that give the appearance of a response to an inactive treatment. These factors include many of the things I listed above, but also other variables that may alter health outcomes or symptoms. See here for a more complete discussion.

The Fallibility of Human Memory: Medical students quickly learn that one of the biggest challenges in taking a medical history is that people are poor historians, which a polite way of saying that human memory is terrible. Anecdotes largely depend upon an individual’s memory of their illness and treatment. This introduces many new variables. There is, for example, a tendency for people to conflate different events in their memory into a single event, or to combine details from various events. There is also a tendency for details to evolve over time to make a story more clean and profound. So people may, in their memory, exaggerate the severity of their symptoms prior to treatment, exaggerate the response to the treatment, clean up the timeline of events so that improvement began very soon after a treatment (rather than before or long after), forget other treatments that were taken, distort what they were told by their various health care providers, etc. I have had countless opportunities to compare a patient’s memory of their illness and treatment to the documented medical records, and the correlation ranges from poor to completely wrong.

For these, and other reasons, scientists have learned not to trust anecdotal reports – or rather to have a realistic assessment of their reliability. This is why it always strikes me as profoundly naive when anyone presents anecdotal evidence as if it is compelling, or even argues that anecdotes should be relied upon as valid evidence.

We also have history to inform our opinions about anecdotes. Western practitioners relied upon the humoral theory of health and illness for thousands of years. Apparently thousands of years of anecdotal experience did not inform them that their treatments were worthless or harmful. Dr. Abrams became wealthy by selling a machine to diagnosis and treat ailments. His devices were widely used, with millions of people swearing by their effectiveness. It worked for them, and their experience was unshakable. When Abrams died it was discovered that his machines (previously protected from inspection) were filled with useless random machine parts. At the turn of the century radioactive tonics were popular, until prominent proponents began seeing the ill effects of radiation poisoning.

The point of these examples is that anecdotal evidence led many people to conclude that these interventions worked. They are useful examples because they are no longer accepted, humoral theory was replaced by scientific medicine, Abrams devices were dramatically exposed, and radiation therapy is directly harmful. But for treatments that are not directly harmful (and least not in an obvious way) or where there is no “man behind the curtain” to dramatically expose, all we have are the anecdotes – and clearly they are not reliable.

Even in mainstream medicine we have learned to distrust anecdotal evidence, even our own. The history of medicine is strewn with treatments that seemed to work but then were abandoned when scientific evidence showed otherwise. The classic example of this is mammary artery bypass for cardiac angina – it seemed anecdotally to work, but it didn’t.

But should anecdotes play any role in medical evidence? Yes, but a very minor and clearly defined one. Anecdotes, with all their weaknesses, are real life experience. It is possible that a treatment does in fact work and personal experience may be the first indication that there is a meaningful biological effect in play. But here are two limiting factors in how anecdotes should be incorporated into medical evidence:

The first is that anecdotes should be documented as carefully as possible. This is a common practice in scientific medicine, where anecdotes are called case reports (when reported individually) or a case series (when a few related anecdotes are reported). Case reports are anecdotal because they are retrospective and not controlled. But it can be helpful to relay a case where all the relevant information is carefully documented – the timeline of events, all treatments that were given, test results, exam findings, etc. This at least locks this information into place and prevents further distortion by memory. It also attempts to document as many confounding variables as possible.

The second criterion for the proper use of anecdotes in scientific medicine is that they should be thought of as preliminary only – as a means of pointing the way to future research. They should never be considered as definitive or compelling by themselves. Any findings or conclusions suggested by anecdotal case reports need to be later verified by controlled prospective clinical studies.

Understanding the nature and role of anecdotes is vital to bridging the gap between the proponents of science-based medicine and believers in dubious or sectarian health practices (as well as the public at large). In my experience it is often the final point of contention between these two camps.

It is interesting to note that the scientific community has long ago made up its collective mind about the weaknesses and role of anecdotes. Logic and the lessons of history speak very clearly on this issue. But there are forces at work today that want to turn back the clock on scientific progress – they want to bring back anecdotes as a reliable source of medical evidence, essentially returning to the pre-scientific era of medicine. In some cases this is done out of frustration – that controlled scientific data has not validated a prior strongly held belief. In other cases it seems to be a calculated attempt to lower the bar of evidence to admit treatments that have not been validated by solid scientific evidence. In either case, this is not in the best interest of the health of the public.

Founder and currently Executive Editor of Science-Based Medicine Steven Novella, MD is an academic clinical neurologist at the Yale University School of Medicine. He is also the host and producer of the popular weekly science podcast, The Skeptics’ Guide to the Universe , and the author of the NeuroLogicaBlog , a daily blog that covers news and issues in neuroscience, but also general science, scientific skepticism, philosophy of science, critical thinking, and the intersection of science with the media and society. Dr. Novella also has produced two courses with The Great Courses , and published a book on critical thinking - also called The Skeptics Guide to the Universe .

• Posted in: Science and Medicine

Posted by Steven Novella

Understanding Anecdotal Evidence in Psychology

Anecdotal evidence is a common phenomenon in psychology, but what exactly does it entail? This article will explore the various types of anecdotal evidence used in psychology, such as personal stories, case studies, testimonials, and expert opinions.

We will also delve into the limitations and potential biases associated with anecdotal evidence, including confirmation bias and self-serving bias. We will discuss how to use anecdotal evidence in a balanced way, along with alternatives such as empirical research and experimental studies. Stay tuned to learn more about the role of anecdotal evidence in psychology!

• Anecdotal evidence is based on personal stories, case studies, testimonials, and expert opinions.
• It can be limited by biases such as confirmation bias, self-serving bias, and hindsight bias.
• To use anecdotal evidence in a balanced way, acknowledge its limitations, use it as a starting point, and combine it with other types of evidence.
• 1 What Is Anecdotal Evidence?
• 2.1 What Are the Limitations of Anecdotal Evidence in Psychology?
• 3.1 Personal Stories
• 3.2 Case Studies
• 3.3 Testimonials
• 3.4 Expert Opinions
• 4.1 Confirmation Bias
• 4.2 Self-Serving Bias
• 4.3 Hindsight Bias
• 5.1 Acknowledge Its Limitations
• 5.2 Use It as a Starting Point
• 5.3 Combine It with Other Types of Evidence
• 6.1 Empirical Research
• 6.2 Experimental Studies
• 6.3 Meta-Analysis
• 7.1 What is anecdotal evidence in psychology?
• 7.2 Why is anecdotal evidence considered unreliable in psychology?
• 7.3 How is anecdotal evidence different from scientific evidence in psychology?
• 7.4 What are some examples of anecdotal evidence in psychology?
• 7.5 How can understanding anecdotal evidence be useful in psychology?
• 7.6 How can one distinguish between anecdotal evidence and scientific evidence in psychology?

What Is Anecdotal Evidence?

Anecdotal evidence refers to information or data that is based on personal experiences, opinions, or observations rather than scientific evidence.

Unlike scientific evidence, which relies on systematic research methods and controlled experiments to ensure objectivity and reliability, anecdotal evidence is subjective and often influenced by personal biases or individual perceptions.

One of the key limitations of anecdotal evidence is its susceptibility to biases such as confirmation bias , where individuals actively seek out information that confirms their preexisting beliefs, and self-serving bias , which leads people to interpret events in a way that benefits themselves.

These biases can distort the interpretation of anecdotal data, making it less trustworthy and open to misinterpretation compared to empirical evidence collected through rigorous scientific processes.

How Is Anecdotal Evidence Used in Psychology?

Anecdotal evidence is commonly utilized in psychology to illustrate specific cases, support hypotheses, and explore cognitive biases in human behavior.

It serves as invaluable material for psychologists to draw from, offering real-life examples that can shed light on complex theories and concepts. By sharing personal narratives or testimonials, anecdotal evidence allows researchers to bridge the gap between theory and practice, making theories more relatable and tangible for a broader audience.

Anecdotal evidence plays a crucial role in forming initial hypotheses by providing a starting point for further investigation. This informal type of data can inspire research questions and guide the development of more structured experiments and studies to test these initial ideas.

When examining phenomena like the placebo effect or cultural fallacies , anecdotal evidence often serves as the starting point for exploring these complex issues. It can offer insights into how individuals perceive and interpret certain situations, prompting researchers to delve deeper into the underlying mechanisms at play.

It is essential to approach anecdotal evidence with caution, as it can be subject to cognitive biases and inaccuracies. Therefore, psychologists emphasize the necessity of conducting controlled experiments to validate anecdotal claims and ensure the reliability and validity of the findings. By combining anecdotal accounts with rigorous scientific methods, researchers can minimize the potential for bias and draw more robust conclusions about human behavior and cognition.

What Are the Limitations of Anecdotal Evidence in Psychology?

While anecdotal evidence can offer valuable insights, it is crucial to acknowledge its limitations in psychology, particularly in terms of establishing causation, generalizability, and emotional biases.

Anecdotal evidence, being based on individual experiences, may lack the ability to establish direct causal relationships between variables due to the absence of controlled conditions.

The generalizability of findings from anecdotes is limited as they represent specific occurrences rather than the broader population.

Emotional biases inherent in anecdotes can cloud judgment and lead to subjective interpretations, potentially skewing the results.

Reliance on anecdotes alone can pose challenges in drawing definitive conclusions, as individual cases may not accurately reflect wider trends or patterns.

Therefore, the importance of incorporating statistical evidence, peer-reviewed studies, and rigorous methodologies emerges to validate and strengthen psychological research findings.

What Are the Types of Anecdotal Evidence in Psychology?

In psychology, anecdotal evidence encompasses various types, including personal stories , case studies, testimonials, and expert opinions, each offering distinct insights into human behavior and cognitive processes.

Anecdotal evidence in psychological research serves as a valuable tool in gaining a deeper understanding of individual experiences and behavior patterns. Personal narratives, in the form of autobiographical recounts or qualitative accounts , provide unique perspectives that shed light on the complexities of the human mind.

Case studies, such as the detailed examination of specific patients or subjects, offer in-depth analyses of rare psychological phenomena or treatment outcomes. These in-depth explorations allow researchers to delve into intricate behavioral patterns and psychopathological traits.

Testimonials from individuals who have undergone psychological interventions or therapeutic treatments can offer valuable insights into the efficacy of certain approaches or therapies.

Personal Stories

Personal stories serve as compelling forms of anecdotal evidence in psychology, offering insights into individual beliefs, societal stereotypes, and the persuasive power of narrative accounts.

These narratives can have a profound impact on how people perceive themselves and others, as they provide a glimpse into the lived experiences of individuals.

By sharing personal stories, individuals can challenge prevailing stereotypes, foster empathy, and promote understanding.

In research and clinical settings, personal narratives are often used to illustrate complex psychological concepts in a relatable manner, evoke emotional responses, and provide a human element to data and statistics.

Case Studies

Case studies offer in-depth examinations of individual cases or phenomena, providing valuable insights into specific behaviors, conditions, or treatments within a controlled research environment.

These detailed investigations allow psychologists to delve deeply into unique situations, offering a nuanced understanding of complex human experiences. By showcasing rare conditions or atypical responses, case studies shed light on aspects that may be overlooked in larger-scale studies. To ensure credibility, researchers must rigorously validate their data and findings, guarding against biases and confounding variables. Integrating multiple case studies can lead to patterns that enhance existing psychological theories, fostering continuous development in the field.

Testimonials

Testimonials represent firsthand accounts of experiences or outcomes, often influenced by the availability heuristic, superstitions, or perceptions of effectiveness in various contexts.

These personal narratives play a crucial role in psychology as they offer individuals real-life examples to relate to. The availability heuristic, a mental shortcut where people rely on readily available information when making decisions, can lead them to give more weight to anecdotal evidence. This psychological phenomenon can make testimonials incredibly persuasive, as they tap into individuals’ subconscious tendencies to trust familiar or easily recalled information.

Expert Opinions

Expert opinions provide valuable insights and recommendations based on professional knowledge and experience, informing decisions in areas such as career advice, product reviews, and psychological research.

These insights serve as a guiding light for individuals seeking direction in complex choices or uncertainties, steering them towards informed choices.

Evaluating expert opinions in psychology involves considering factors such as the specialist’s credentials, experience, and any potential biases that may influence their perspective. This critical assessment is crucial in ensuring that the information provided is reliable and applicable to the context at hand.

Expert opinions play a crucial role in shaping the landscape of psychological research by offering nuanced interpretations and expert analysis in various subfields.

Researchers often rely on these opinions to refine their study designs, validate findings, or consider alternative viewpoints to broaden their understanding of complex phenomena.

It’s vital for researchers to discern between expert opinions that enrich their work and those that may lead them astray, ensuring that their conclusions are well-founded and robust in the face of scrutiny.

What Are the Potential Biases in Anecdotal Evidence?

Anecdotal evidence is susceptible to various biases, including cognitive biases, logical fallacies, emotional influences, and correlations that may distort the interpretation and validity of anecdotal accounts.

For instance, confirmation bias can lead individuals to seek out information that confirms their existing beliefs, disregarding contradictory evidence. The availability heuristic may cause reliance on readily available examples that support a particular viewpoint, overlooking more comprehensive data. Survivorship bias can distort perceptions by focusing on successful outcomes, neglecting instances of failure. Emotional factors, such as personal investment in a certain narrative, can cloud judgment and sway perceptions.

These biases can significantly impact the credibility and reliability of anecdotal information, making it essential to approach such accounts with caution and skepticism. When individuals hold preconceived notions or strong emotional attachments to specific outcomes, it becomes challenging to objectively evaluate the veracity of anecdotal evidence.

When attempting to draw conclusions from anecdotal data, the challenges of inferring causation or correlations arise. Without controlled experiments or systematic data collection, establishing causal relationships based on individual stories can be misleading. Therefore, it is crucial to critically assess the validity and generalizability of anecdotal accounts in psychological research, recognizing their limitations and potential biases.

Confirmation Bias

Confirmation bias influences individuals to seek or interpret information that confirms their pre-existing beliefs or hypotheses, leading to selective attention to supportive anecdotal evidence in decision-making processes.

For example, if someone strongly believes in the effectiveness of a particular diet, they may only notice and remember the success stories of individuals who lost weight following that diet, while ignoring or downplaying instances where it did not work. This tendency can impact various aspects of life, such as how people perceive the credibility of news sources based on their alignment with personal opinions, or how individuals make important decisions like investments or medical treatments.

One way to combat confirmation bias is through actively seeking out information that challenges one’s beliefs and encourages objective consideration of all perspectives. Engaging in critical thinking techniques, like questioning assumptions and examining the reliability of sources, can help individuals navigate through anecdotal accounts more thoughtfully and make evidence-based judgments.

Self-Serving Bias

Self-serving bias involves individuals attributing positive outcomes to their abilities or actions while blaming external factors for negative results, affecting the reliability and objectivity of anecdotal evidence.

When individuals are influenced by self-serving bias, they may subconsciously alter their stories or memories to make themselves look better or to avoid taking responsibility for failures. This bias can lead to a distortion of facts and a skewed representation of reality in anecdotal accounts, potentially diminishing their credibility. It is essential to recognize how self-serving bias plays a role in reinforcing stereotypes and perpetuating misconceptions by highlighting only favorable experiences while overlooking setbacks.

Self-serving bias can contribute to survivorship bias in anecdotal narratives, where only the stories of those who succeed are shared, neglecting the experiences of those who didn’t make it. This selective sharing can create a misleading perception of reality and distort the understanding of actual outcomes in various situations.

Therefore, it is imperative for individuals to reflect on their personal biases and motivations when evaluating anecdotal evidence, especially in psychological research, to ensure a more objective and accurate interpretation of the information presented.

Hindsight Bias

Hindsight bias leads individuals to perceive past events as more predictable or preventable after knowing the outcome, impacting the retrospective evaluation of anecdotal evidence and the effectiveness of interventions.

This cognitive bias can significantly influence how people view the accuracy and reliability of anecdotal accounts when looking back on past events. Hindsight bias can lead individuals to believe that they could have foreseen an outcome or made a different decision if they had known the end result in advance. This inclination can distort the way individuals assess the effectiveness of interventions or decisions based solely on anecdotal evidence, potentially skewing their perspectives on what could have been done differently.

How Can Anecdotal Evidence Be Used in a Balanced Way?

Balanced utilization of anecdotal evidence involves acknowledging its inherent limitations, using it as a starting point for further investigation, and integrating it with other forms of evidence to mitigate biases and enhance the credibility of research.

Anecdotal evidence can be a valuable asset to psychological research, offering researchers a glimpse into real-world experiences and phenomena. Researchers must tread carefully, recognizing that anecdotal evidence is subjective and prone to interpretation. It serves as a precursor to hypothesis generation, providing researchers with leads that can guide their more structured investigations. When supplementing anecdotal evidence with empirical studies or controlled experiments, researchers can validate or refine their initial insights, ensuring a more robust foundation for their findings.

Acknowledge Its Limitations

Acknowledging the limitations of anecdotal evidence involves recognizing its subjective nature, potential biases, and lack of generalizability, prompting researchers to exercise caution in drawing definitive conclusions based solely on anecdotal data.

While anecdotal evidence can offer valuable insights into individual experiences and perspectives, its reliance on personal accounts makes it susceptible to memory distortions, selective recall, and subjective interpretations. This highlights the importance of transparency in reporting anecdotal data, disclosing any potential biases or limitations that may influence the quality of the information presented.

Researchers face the challenge of establishing the validity and reliability of anecdotal evidence, necessitating rigorous methodological scrutiny to ensure the credibility of findings.

Use It as a Starting Point

Employing anecdotal evidence as a starting point in research involves using initial observations or narratives to formulate hypotheses, explore potential correlations, and guide further investigation into psychological phenomena.

Anecdotal evidence can provide researchers with valuable insights that help in formulating research questions and constructing theoretical frameworks. These accounts often serve as a vital spark that ignites further investigation into specific phenomena or behaviors of interest. By identifying unique patterns or connections within anecdotal stories, researchers can develop a roadmap for empirical studies aimed at validating these initial observations.

Combine It with Other Types of Evidence

Integrating anecdotal evidence with other forms of evidence involves synthesizing personal narratives, case studies, or testimonials with empirical research, statistical data, and theoretical frameworks to construct comprehensive arguments and hypotheses in psychology.

For instance, in studying the effects of mindfulness meditation on reducing anxiety, researchers might gather quantitative data on physiological responses during meditation sessions. To grasp the subjective experiences and motivations underlying these changes, incorporating personal stories of individuals who practice mindfulness could shed light on the nuances of its impact.

When examining the efficacy of cognitive-behavioral therapy, combining outcome measures with real-life accounts of individuals undergoing therapy can offer contextual insights into the effectiveness of the intervention. By weaving together these diverse sources of information, psychologists can present a richer tapestry of understanding that transcends mere numbers and statistics.

What Are the Alternatives to Anecdotal Evidence in Psychology?

In psychology, alternatives to anecdotal evidence include empirical research methods , experimental studies , and meta-analyses , which emphasize systematic investigations, controlled interventions, and comprehensive statistical analyses to validate psychological theories and hypotheses.

Empirical research methods entail the collection and analysis of data through direct observation or experimentation to establish correlations and causal relationships.

Experimental studies involve the manipulation of variables under controlled conditions to assess the impact of specific factors on behavior or mental processes.

Meta-analyses integrate data from multiple studies to provide a quantitative synthesis of findings, offering a more comprehensive and reliable understanding of a particular research topic.

By employing controlled studies, researchers can minimize confounding variables, increase internal validity, and enhance the reliability of their results.

Empirical Research

Empirical research in psychology involves the systematic collection and analysis of data through controlled observations, experimental manipulations, and statistical analyses to test hypotheses, establish causal relationships, and refine psychological theories.

This approach emphasizes the importance of methodological rigor, which ensures that the study design and data collection methods are carefully planned to minimize biases and errors. By adhering to strict research protocols, researchers can maintain objectivity throughout the investigation process, avoiding subjective interpretations that might skew the results.

The hallmark of empirical research lies in its replicability , where the findings can be independently verified by other researchers through repeated experiments or observations. This not only enhances the credibility of the study but also allows for the establishment of robust scientific knowledge.

Experimental Studies

Experimental studies in psychology involve manipulating variables in a controlled environment to investigate causal relationships, draw conclusions about psychological phenomena, and mitigate biases such as survivorship bias or confounding variables.

These types of studies play a pivotal role in advancing our understanding of human behavior by testing specific hypotheses through structured experiments. By implementing random assignment techniques, researchers can distribute participants evenly across experimental conditions, reducing the impact of individual differences and increasing the validity of results.

The systematic controls embedded within experimental designs ensure that extraneous variables are minimized, allowing researchers to isolate the effects of the manipulated variables accurately. This rigorous approach enhances the credibility of the conclusions drawn from the experiments and provides a solid foundation for building theoretical frameworks within the field of psychology.

Meta-Analysis

Meta-analysis in psychology involves synthesizing results from multiple studies to examine patterns, effect sizes, and inconsistencies across research findings, offering a comprehensive overview of the evidence base and informing decision-making processes.

Meta-analysis serves as a powerful tool in the realm of psychological research, providing a systematic approach to pool findings from various studies and derive more reliable conclusions. By aggregating data from multiple sources, it enables researchers to evaluate the overall impact of interventions, treatments, or phenomena, thus enhancing the robustness of the findings. Through meticulous analysis of study outcomes, meta-analytical techniques play a crucial role in identifying commonalities, discrepancies, and trends, leading to a deeper understanding of the subject matter.

Frequently Asked Questions

What is anecdotal evidence in psychology.

Anecdotal evidence in psychology refers to information or observations that are based on personal experiences or individual cases rather than scientific evidence or empirical research.

Why is anecdotal evidence considered unreliable in psychology?

Anecdotal evidence is considered unreliable in psychology because it is based on personal biases and individual experiences, making it difficult to generalize to larger populations or draw conclusive and accurate conclusions.

How is anecdotal evidence different from scientific evidence in psychology?

Anecdotal evidence is based on individual experiences and personal observations, while scientific evidence is obtained through rigorous research methods and is supported by statistical analysis and replicable results.

What are some examples of anecdotal evidence in psychology?

Some examples of anecdotal evidence in psychology include personal stories or testimonials about the effectiveness of a certain therapy or treatment, and individual accounts of a particular psychological phenomenon.

How can understanding anecdotal evidence be useful in psychology?

Understanding anecdotal evidence in psychology can be useful in generating hypotheses and ideas for further research, as well as providing insight into individual experiences and perspectives.

How can one distinguish between anecdotal evidence and scientific evidence in psychology?

One can distinguish between anecdotal evidence and scientific evidence in psychology by considering the source of the information, the methodology used to obtain it, and whether the results are supported by other research studies.

Dr. Henry Foster is a neuropsychologist with a focus on cognitive disorders and brain rehabilitation. His clinical work involves assessing and treating individuals with brain injuries and neurodegenerative diseases. Through his writing, Dr. Foster shares insights into the brain’s ability to heal and adapt, offering hope and practical advice for patients and families navigating the challenges of cognitive impairments.

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The Comparative Study of Anecdotal Vs Scientific Evidence in 2024

This article offers an in-depth comparison between anecdotal and scientific evidence, emphasizing their respective strengths and limitations.

It explores the objective nature of scientific evidence and the subjective characteristics of anecdotal evidence.

The influence of both types on decision-making, particularly in healthcare and education, is discussed.

The aim is to enhance readers’ understanding of evidence evaluation, promoting critical thinking and informed decision-making in interpreting and applying scientific news.

Key Takeaways

• Anecdotal evidence is limited in value due to bias and personal preconceptions.
• Scientific evidence relies on more rigorous methods and is less prone to error.
• Relying exclusively on anecdotal evidence can lead to overgeneralisation and bias.
• Understanding research terms helps in evaluating the rigor of studies.

Understanding the Basis of Anecdotal and Scientific Evidence

Drawing from our comprehensive knowledge, understanding the basis of anecdotal and scientific evidence involves distinguishing between the methodological rigor of scientific research and the subjective nature often associated with anecdotal accounts.

Anecdotal evidence feeds on personal experiences. It lacks the stringent checks and controls that you will find in scientific research. This is one of the most noticeable differences with scientific evidence. Anecdotal evidence is subjective and it can lead to biased perceptions while scientific evidence is backed up by rigorous research methodology. This results in a much more trust-worthy basis for drawing conclusions.

However, how does anecdotal evidence contrast with scientific evidence? While anecdotal evidence can offer insights into individual experiences, it cannot be generalised like scientific evidence. Hence, it’s crucial to understand the differences to make informed decisions.

The Role and Impact of Scientific Evidence in Research

In the realm of research, scientific evidence plays a crucial role by providing a robust and reliable foundation for conclusions, with its impact being seen in the thousands of studies conducted annually worldwide. As a cornerstone of modern science, it acts as a critical tool, guiding decision-making, validating theories, and contributing to advancements in various fields. However, understanding, interpreting, and applying scientific evidence requires a certain level of expertise and critical thinking.

Thus, scientific evidence holds paramount significance in research, shaping our understanding of the world.

Exploring Anecdotal Evidence: Pros and Cons

If you want to explore the realm of anecdotal evidence you need to know that even though it is appealing and leads to personal relevance, you are also exposed to overgeneralisation. This type of evidence is based mainly on personal testimonials which sometimes might not be accurate for different reasons. 

Benefits of Anecdotal Evidence:

• Personal relevance: Stories resonate with us, making the evidence relatable and memorable.
• Easy comprehension: The information is usually straightforward, making it accessible to a wide audience.

Drawbacks of Anecdotal Evidence:

• Susceptibility to Bias: Personal perceptions can color the evidence, leading to skewed interpretations.
• Risk of Overgeneralisation: A few experiences can be mistakenly applied to broader populations or contexts.

Key Differences Between Anecdotal and Scientific Evidence

Unquestionably, the key differences between anecdical and scientific evidence lie primarily in their collection methods, reliability, and susceptibility to bias.

Scientific evidence is derived from rigorous, systematic and objective methodologies, which are replicable and verifiable. This evidence is less susceptible to bias, making it a more reliable source of information.

On the other hand, anecdotal evidence feeds on personal experiences and their testimonies. These are subjective and can be biased. It doesn’t have the rigour and reproducibility of scientific methodologies and it leads to a higher chance of inaccuracy.

While anecdotal evidence can provide valuable insights and context, it should not be used as a standalone source of evidence due to its inherent limitations.

Hence, a balance between anecdotal and scientific evidence should be sought for a comprehensive understanding.

Case Studies: Anecdotal and Scientific Evidence in Action

How do case studies illustrate the application of anecdotal and scientific evidence in real-world scenarios, and what insights can we derive from these instances?

Case studies provide an opportunity to apply both types of evidence in a real-world context. They allow for a deep exploration of specific situations, offering insights into how anecdotal and scientific evidence can be used together for a more comprehensive understanding.

• Anecdotal Evidence in Case Studies
• Personal experiences and testimonies provide rich, qualitative data.
• Offers detailed insights, but may be subjective and prone to biases.
• Scientific Evidence in Case Studies
• Provides objective, measurable data obtained through rigorous methods.
• Can validate or challenge anecdotal evidence.
• Insights from Case Studies
• Balance between anecdotal and scientific evidence is crucial.
• Strengthens the validity of findings and facilitates informed decision-making.

Frequently Asked Questions

What is the psychological reasoning behind the persuasive power of anecdotal evidence over scientific evidence.

The persuasive power of anecdotal evidence often stems from its emotional resonance and relatability, which can make it seem more compelling to individuals, despite its lack of scientific rigour or broader applicability.

How Can Scientific Research Be Made More Accessible and Understandable to the General Public?

Making scientific research accessible to the public involves simplifying complex jargon, summarising key findings, utilising visuals, and providing real-world applications. Public engagement initiatives and open-access journals also enhance accessibility and understanding.

What Are Some Strategies to Educate People on the Importance of Scientific Evidence and the Limitations of Anecdotal Evidence?

Strategies to educate people on the importance of scientific evidence and the limitations of anecdotal evidence include public awareness campaigns, integrating science literacy in education, and promoting critical thinking skills in various platforms.

How Does the Spread of Misinformation and Reliance on Anecdotal Evidence Impact Policy Making in Fields Like Healthcare and Education?

Misinformation and reliance on anecdotal evidence can negatively impact policy making in healthcare and education, potentially leading to ineffective or harmful strategies, due to their lack of rigorous testing and susceptibility to bias.

Can Anecdotal Evidence Ever Be Useful or Reliable in Certain Circumstances or Fields?

Anecdotal evidence can indeed be useful in certain circumstances, particularly for generating hypotheses or understanding individual experiences. However, its reliability is limited due to the potential for bias and lack of rigorous testing.

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This comparative study underscores the importance of understanding the differences and nuances of anecdotal and scientific evidence.

While scientific evidence offers objectivity and replicability, anecdotal evidence provides depth, context, and personal perspectives.

Despite its potential bias, anecdical evidence can guide research directions and inspire scientific inquiry.

Thus, both types of evidence should be critically evaluated for an informed understanding of science news, aiding in effective decision-making in various fields such as healthcare and education.

Discover the ScioWire research newsfeed: summarised scientific knowledge ready to digest.

Anecdotal Fallacy (29 Examples + Description)

If you've ever made a decision based on a story or personal experience, you're not alone. Stories shape how we understand the world, but they can also mislead us.

An Anecdotal Fallacy occurs when someone relies on personal experiences or individual cases as evidence for a general claim, overlooking larger and more reliable data.

Get ready to learn everything you need to know about the anecdotal fallacy. In this article, we'll take you through its history, its psychological roots, and its impact on your daily decisions. Along the way, we'll provide real-world examples to make this psychological concept come alive.

What is an Anecdotal Fallacy?

You've probably been in a situation where someone tries to prove a point by sharing a personal story. "My uncle smoked for years and lived to be 90, so smoking can't be that bad," they might say. This kind of reasoning might seem convincing at first. After all, a story paints a vivid picture.

But here's the catch: Anecdotal fallacy is the faulty logic that makes such statements problematic. It's when someone uses a personal story or a few individual cases to make a broad claim. Just because it happened to one person doesn't mean it's a universal truth. The bigger picture often involves research and data that can offer a more accurate view.

This kind of reasoning is an example of a logical fallacy. Fallacies are logical errors, usually in arguments, that people make which lead to inconsistent reasoning. Any instance where testimonials are presented to prove a theory is not a logical form. Such evidence is often used in decision making but since it's cherry picked, there's no way to prove it will occur for everyone, or even more than one time.

Other Names for This Fallacy

• Anecdotal Evidence Fallacy
• Empirical Fallacy
• Case Study Fallacy

Similar Logical Fallacies

• Hasty Generalization : Making a broad claim based on insufficient evidence.
• Appeal to Authority : Believing a claim is true because an "expert" says so.
• Post Hoc Ergo Propter Hoc : Assuming that because one event follows another, the first caused the second.
• Cherry-Picking : Selecting only the evidence that supports a particular claim, while ignoring counter-evidence.
• Confirmation Bias : Paying attention only to information that confirms one's existing beliefs.

The term "anecdotal fallacy" doesn't have a long or glamorous history, but it's rooted in the ancient study of logic and reasoning. Philosophers like Aristotle laid the groundwork for identifying different types of faulty logic.

The modern term was coined to specify the misuse of personal anecdotes as credible evidence, especially in the era of social media, where such stories are shared widely and quickly.

29 Examples

1) vaccinations.

"My kids never got vaccinated, and they're perfectly healthy, so vaccines aren't necessary."

This argument is an anecdotal fallacy because the health of a few individuals isn't representative of the population at large. Vaccines go through rigorous testing and are recommended based on extensive scientific evidence, not isolated cases.

2) Organic Foods

"My neighbor only eats organic food and lived to 95, so organic food must be the key to a long life."

Here, an individual case is used to make a sweeping claim about organic foods. This overlooks other potential factors like genetics, lifestyle, and medical care, not to mention scientific research on the subject.

3) Exercise

"I never exercise and I'm in great shape. Exercise is overrated."

Using personal experience to discredit science and the importance of exercise is an anecdotal fallacy. A single case isn't enough to disprove the body of evidence supporting the benefits of regular exercise.

4) Car Brands

"My Toyota has never had a problem, so Toyotas are the most reliable cars."

While personal experience with a Toyota may be positive, it doesn't account for the vast amount of data collected on vehicle reliability. Other people might have had different experiences, and there are studies and statistics that provide a more comprehensive view.

5) College Degrees

"My uncle didn't go to college and he's a millionaire, so college is a waste of time."

Using a single success story to argue against the value of higher education ignores the broader data. Studies consistently show that, on average, people with college degrees earn more over their lifetimes than those without.

6) Stock Market

"I invested in Bitcoin and made a fortune, so investing in Bitcoin is a guaranteed win."

This anecdotal fallacy ignores the volatile nature of cryptocurrencies and the experiences of those who lost money. It's a risk that shouldn't be judged by individual successes. It also plays into cognitive biases of people who are easily swayed by emotional arguments.

7) Climate Change

"It's snowing outside, so global warming can't be real."

This is an anecdotal fallacy because it takes a local, short-term condition and uses it to question a long-term, global trend. Climate is based on long-term averages, not individual weather events. Such anecdotal evidence mimics illustrative story telling rather than more reliable statistics. A few instances doesn't rule out the explanation of many researchers.

8) Veganism

"I went vegan and my health problems disappeared, so everyone should go vegan."

Using proof of a personal health transformation to advocate for veganism for everyone is an anecdotal fallacy. Individual results can vary, and a single story doesn't negate the need for comprehensive scientific research. Imagine someone having a broccoli based diet or a low fat diet and saying the same thing!

9) Alternative Medicine

"My friend tried acupuncture and her back pain went away, so acupuncture cures back pain."

While it's great that the individual found relief, this is an anecdotal fallacy because one person's experience isn't enough to establish acupuncture as a definitive cure for back pain.

10) Political Policies

"My taxes went down last year, so the new tax policy is beneficial for everyone."

This is an anecdotal fallacy because one person's tax experience doesn't provide a comprehensive view of the policy's impact on all income levels and demographics. Although, the hope here is to create a bandwagon effect where people will vote for the party because they think the party is doing good things.

11) Coffee Consumption

"I drink five cups of coffee a day and I'm fine, so coffee can't be that bad."

Personal tolerance to coffee doesn't negate the various studies on its health impacts. This is an anecdotal fallacy.

12) Astrology

"I'm a Libra and I read my horoscope daily; it's always accurate so astrology must be true."

This claim is based on one individual's experience and ignores the need for scientific evidence to support astrology's validity.

13) Safety Measures

"I never wear a seatbelt and I've never had an accident, so seatbelts are unnecessary."

One person's good luck doesn't invalidate the statistics proving that seat belts save lives.

14) Job Market

"I got a job right after college, so the job market must be good."

This overlooks larger economic factors and the experiences of others who are struggling to find employment.

15) Allergies

"My sister is allergic to cats, so all cats must be bad for people."

This is an anecdotal fallacy. Allergies are individual reactions and not everyone has the same sensitivities.

16) Smoking

"My grandfather smoked all his life and lived to be 90, so smoking can't be that bad."

An individual case like this can't negate the overwhelming evidence that smoking is harmful to health. Just because one person is cancer free doesn't mean we can come to the conclusion that smoking does not cause cancer.

17) Nutrition

"I ate a chocolate bar and didn't gain weight, so chocolate doesn't contribute to weight gain."

This is an anecdotal fallacy because it takes a one-time event and uses it to make a broad claim, ignoring factors like metabolism and overall diet. Not to mention that if the event occurred consecutively, the person would probably gain weight.

18) Social Media

"I've never experienced harassment online, so the internet is a safe space."

This ignores the experiences of many others who have faced harassment or other dangers online.

19) Religion

"My prayers were answered, so that proves that my faith is the true one."

This is an anecdotal logical fallacy because it assumes a personal experience can validate a belief system for everyone else.

20) Economic Status

"I worked my way through college without debt, so anyone can do it."

This anecdotal fallacy ignores other factors such as rising tuition costs, family support, and varying wages.

21) Video Games

"I play violent video games and I'm not aggressive, so they don't affect behavior."

This is an anecdotal fallacy because one person's experience doesn't refute studies showing a potential link between violent video games and aggression.

22) Alcohol

"My dad drinks every day and he's fine, so alcohol is not harmful."

Ignoring the vast amount of research showing the risks associated with alcohol consumption is an anecdotal fallacy.

23) Parenting Styles

"My parents were strict and I turned out fine, so strict parenting is the best."

This is an anecdotal fallacy because it assumes that what worked for one person will work for everyone.

24) Pharmaceuticals

"My friend stopped taking her meds and felt better, so medications are unnecessary."

Such an argument that ignores the larger body of evidence on the effectiveness of medications is an anecdotal fallacy. It's important to make sure that a properly conducted study exists to show the correct treatment.

"I only need 4 hours of sleep to function, so the 8-hour sleep recommendation is exaggerated."

This is an anecdotal fallacy because individual differences in sleep needs don't negate the extensive research on the importance of sleep. Oner person's experience is a too small sample size. Proof would require a representative sample to conclude reliable statistics rather than someone's own experience.

26) Natural Disasters

"My town has never experienced an earthquake, so they must be really rare."

This is an anecdotal fallacy because it takes a localized experience and applies it universally, ignoring geological data and history.

27) Animal Behavior

"My dog hates the mailman, so all dogs must hate mailmen."

This uses a single observation to make a sweeping and dangerous generalization, which is an anecdotal fallacy.

28) Health Supplements

"I tried a health supplement and felt more energetic, so it must work for everyone."

This form of anecdotal fallacy assumes that a single positive experience can be generalized to everyone, ignoring biological differences and placebo effects.

29) Online Shopping

"I bought a laptop online and it was a great deal, so online shopping is always cheaper."

This anecdotal fallacy overlooks the variability in pricing and discounts both online and in physical stores.

The Psychological Mechanisms Behind It

The brain is wired to love stories. From early human history, storytelling has been a way to share knowledge and experience. Because of this, when you hear an anecdote, it often feels more compelling than dry statistics or facts. It's relatable and easy to remember.

This is a psychological bias known as the " availability heuristic ," where information that's easy to recall has more influence over your thinking. You're more likely to believe something if you can easily think of an example, and personal stories fit the bill.

However, this emotional connection to stories can cloud your judgment. You might focus on the anecdote's immediate appeal, forgetting that it's just a single data point. This is why the anecdotal fallacy is so pervasive.

It preys on the brain's natural tendency to prioritize personal stories over broad evidence. When you give undue weight to an anecdote, you're engaging in " confirmation bias ," where you focus on information that confirms your existing beliefs and ignore data that challenges them.

The Impact of the Anecdotal Fallacy

The influence of the anecdotal fallacy can be wide-ranging and sometimes harmful. In everyday conversations, falling for this fallacy might not seem like a big deal. But when it comes to important decisions—like healthcare, policy-making, or personal finance—relying on anecdotes instead of evidence can lead to poor outcomes.

For example, if people start believing that vaccines are harmful based on a single story they heard, this can lead to lower vaccination rates and ultimately, public health risks.

On a societal level, the anecdotal fallacy can shape public opinion and even influence laws and regulations, often not for the better.

Additionally, the anecdotal fallacy can also reinforce stereotypes and biases. Since it leans heavily on personal experience or stories, it can perpetuate generalizations about groups of people based on isolated incidents.

This can further social divides and create a more polarized society, as people become more entrenched in their views without a solid basis in comprehensive data or statistical evidence.

How to Identify and Counter It

Spotting an anecdotal fallacy involves a keen eye for the bigger picture. When you hear a claim based on a single story or experience, ask yourself: is this representative of a larger trend or just an isolated case? Be wary when someone tries to make sweeping claims based on limited data.

The key is to look for more comprehensive and compelling evidence that either supports or refutes the anecdote in question. Seek out scientific studies, statistics, or a broader range of experiences to get a more balanced view.

Countering the anecdotal fallacy is about elevating the conversation to focus on more reliable sources of information. If someone is using an anecdote to argue a point, kindly question its validity and ask if there's broader evidence to support the claim. Point out that while the story may be true for one person, it doesn't necessarily apply to everyone.

It's not about discrediting individual experiences, but rather, putting them in their proper context within a larger dialogue grounded in evidence and reason.

Related posts:

• Logical Fallacies (Common List + 21 Examples)
• Genetic Fallacy (28 Examples + Definition)
• Hasty Generalization Fallacy (31 Examples + Similar Names)
• Ad Hoc Fallacy (29 Examples + Other Names)
• Fallacy of Composition (27 Examples + Definition)

Reference this article:

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19 Anecdotal Evidence Examples

Dave Cornell (PhD)

Dr. Cornell has worked in education for more than 20 years. His work has involved designing teacher certification for Trinity College in London and in-service training for state governments in the United States. He has trained kindergarten teachers in 8 countries and helped businessmen and women open baby centers and kindergartens in 3 countries.

Learn about our Editorial Process

Chris Drew (PhD)

This article was peer-reviewed and edited by Chris Drew (PhD). The review process on Helpful Professor involves having a PhD level expert fact check, edit, and contribute to articles. Reviewers ensure all content reflects expert academic consensus and is backed up with reference to academic studies. Dr. Drew has published over 20 academic articles in scholarly journals. He is the former editor of the Journal of Learning Development in Higher Education and holds a PhD in Education from ACU.

Anecdotal evidence refers to when information regarding a phenomenon, activity, or event comes from direct experience or opinions of individuals.

Anecdotal evidence is often shared organically through conversation, such as with old wives’ tales, and may become more credible when people attest to it.

People can be easily influenced by anecdotal accounts and will often follow the advice of someone just based on that individual’s recommendation.

However, advice based on anecdotal evidence can be misleading, sometimes even dangerous, a requires rigorous testing for it to be truly trustworthy empirical evidence held with esteem by scientists and experts.

Anecdotal Evidence Examples

• Weather Predictions: A person might claim that they can predict the weather based on their observation of specific environmental factors, such as the appearance of certain clouds or the behavior of animals. While these predictions might be accurate occasionally, they are not grounded in scientific data or meteorological expertise.
• The Quitter who Landed on his Feet: A man who quit his job with very little savings ended up finding another, even better, job three weeks later. Now, he recommends to anyone who’s unhappy in their job to quit because you’ll land on your feet, too – just like him.
• Supplement Effectiveness: People might claim that a particular dietary supplement or natural product greatly improved their health or cured a specific ailment. These testimonials often lack scientific support but can still influence the decisions of others seeking similar results.
• Bad consumer experience: A man travels on a 10-hour flight with a big brand airline and has a horrible time. Twenty years later, he still says that brand is the word brand of airline in the world.
• Sensationalized media: Often, the media presents outlier case studies due to their sensational nature. But media reports are often simply sensational anecdotal evidence that the reporters have found rather than statistical data.
• Bad parenting: A man decides his neighbor is a terrible parent because he saw her one day unable to control her child. He didn’t see all the other examples of when that woman was being an excellent mother
• Observing that Opposites Attract: Sometimes,anecdotal evidence can be accurate. For example, the common saying that “opposites attract” is based on anecdotal evidence of people observing the oddity of couples that don’t seem to match. Lately, research has studied the validity of this anecdotal evidence. The key finding: romantic relationships are about balance .
• Life Lessons: Life lessons passed on from generation to generation may not be based in the scientific method , the this kind of anecdotal evidence has a lot of credibility nonetheless. For example, a father who tells his son not to get involved in a bad relationship comes from his anecdotal experience, but it’s also great advice.
• Home Remedies: People often share personal anecdotes about the effectiveness of home remedies for various ailments. These stories are based on individual experiences rather than scientific evidence, but they can still influence others to try the remedies themselves.
• Career Advice: A successful professional may offer career advice based on their personal experiences, attributing their success to certain behaviors or decisions. While these anecdotes might be inspiring, they don’t necessarily guarantee similar results for everyone who follows the same path.
• Anecdotal Evidence in Scientific Communication: When anecdotal evidence comes from a trusted expert, it can be very persuasive . As a result, scientists often teach concepts like climate change by appealing to anecdotal evidence (e.g. ‘you’ve noticed it’s gotten hotter since your childhood’). This is actually part of Petty and Cacioppo’s (1986) Elaboration Likelihood Model of Persuasion .
• Product Reviews: A friend raves about a new gadget or appliance that they recently purchased, claiming it has made their life easier. This anecdotal evidence might be compelling, but it doesn’t provide a comprehensive evaluation of the product’s overall quality and effectiveness.
• Superstitions and Beliefs: People may believe in certain superstitions or rituals based on anecdotal evidence. For example, someone might avoid walking under ladders due to a story they heard about someone experiencing bad luck after doing so, despite the lack of any statistical correlation between the action and the outcome.
• Stereotyping: We’ve all heard the saying “birds of a feather flock together.” This is an example of anecdotal evidence where a person stereotypes a whole group of people based upon their experience with one person from within that group.
• Weight Loss Success: Individuals might share stories of losing weight through a specific diet or exercise routine. While these anecdotes can be motivating, they may not be universally applicable or supported by scientific research on the most effective weight loss methods.
• Pet Behavior: Pet owners may share anecdotes about their pets’ unique behaviors or training techniques that have worked for them. These stories, while interesting, might not be applicable to all pets or provide reliable information about animal behavior in general.
• Tennis Player’s Routine: A tennis player has the best game of his life one day after eating three eggs for breakfast. He’s so convinced by this anecdotal evidence that every game day has two start with three eggs and a big cup of coffee or else he’s convinced he will lose the game.
• Effective Study Habits : Students might claim that a specific study technique such as the pomodoro method led to their academic success. So they tell their friends to follow the advice, too. Unfortunately, the pomodoro technique may not work for everyone as we all have our own unique motivations and learning preferences.
• Lucky Charms: A person might carry around a lucky charm in their wallet because the day they found the lucky charm was a very good day for them. They suggest others buy these lucky charms, too, based on their own anecdotal evidence about the charms.

Levels of Evidence: Anecdotal Evidence Ranks Low in Reliability

Practicing psychologists (APA, 2006) rely on a hierarchy of evidence which identifies the degree of validity of evidence based on stringent research parameters.

According to Stegenga (2014), “An evidence hierarchy is a rank-ordering of kinds of methods according to the potential for that method to suffer from systematic bias” (p. 313).

Based on Isoz (2020) .

As seen in this graphic, at the bottom of the hierarchy is anecdotal evidence, which carries no scientific weight and has the highest degree for potential bias.

Is Anecdotal Evidence Ever Useful?

Although anecdotal evidence is not grounded in science or produced as a result of a scientific study, it does have some limited value.

For instance, a person’s description about an experience can be used as a starting point to understanding a given phenomenon.

If several people have similar descriptions, then it may inform a scientist as to common characteristics of an experience which may be the impetus for a scientific inquiry.

In other cases, it is the errors in judgement as a result of anecdotal recollections that can lead to insights into perception and decision-making.

Case Studies of Anecdotal Evidence  

1. the many insights of jean piaget.

Jean Piaget was a Swiss psychologist that developed an incredibly insightful theory of cognitive development. It is a theory that has driven decades of research and become a cornerstone of developmental psychology.

Even though Piaget was a trained professional, his methodology was nearly 100% anecdotal. He observed each of his children and took exhaustive notes on their behavior.

On the emergence of the deliberate action of a newborn, as evidence of intent:

“The child discovers in this way that which has been called in scientific language the “experiment in order to see” (p. 266). The infant is attempting the “discovery of new means through active experimentation” (Piaget, 1956, p. 267).A few years later, Piaget provides anecdotal evidence for what will become officially known as egocentrism . Here is a sample of his observations from The Language and Thought of the Child (1959).

“Our notes show…that at the beginning of his fourth year the child’s speech shows a greater coefficient of ego-centrism (i.e., it is less socialized in character) when speaking with adults than children of his own age (71.2% against 56.2%)” (p. 143).

Piaget had no right to make scientific claims based on this data – it’s purely anecdotal. Nevertheless, it still rings true to this day. Sometimes, anecdotal evidence turns out to be true.

2. Anecdotal Evidence and Criminal Prosecutions

Every year in the United States, thousands of people are convicted of crimes based on eyewitness testimony. That is, based on anecdotal evidence. Most of those witnesses are quite confident in their accounts.

However, psychologist Dr. Elizabeth Loftus (1997) has demonstrated that this form of anecdotal evidence can be quite unreliable.

In fact, under certain conditions, false memories can be created that “feel” accurate, but are not.

“False memories are constructed by combining actual memories with the content of suggestions received from others” ( Loftus, 1997 , p. 75).

One of the first studies was conducted by Loftus and Palmer (1974), which demonstrated that memory could be easily altered simply by changing the way a question is phrased.

This line of research has had a tremendous impact on law enforcement and the credibility of eyewitness testimony .

Anecdotal evidence refers to information that comes from our own experience or someone else’s. It can be very persuasive, especially if it comes from a credible source, such as an expert or trusted friend.

As a source of scientific evidence however, it is considered unreliable. There are many possible biases that can undermine the validity of anecdotal evidence.

Although often harmless, in some contexts, anecdotal evidence can be quite dangerous. For example, research has demonstrated that eyewitness testimony can be easily manipulated.

On the other side of the coin however, anecdotal evidence can be the impetus for a new line of scientific inquiry.

Nearly all of Piaget’s theory of cognitive development was based on anecdotal evidence he gathered by observing his own children. And let’s not forget that our understanding of bystander intervention was sparked by anecdotal accounts of a terrible tragedy. 

So, while scientists tend to discount the value of anecdotal evidence, it has played a significant role in many highly influential in psychological studies.

APA Presidential Task Force on Evidence-Based Practice (2006). Evidence-based practice in psychology. The American Psychologist , 61 (4), 271–285. https://doi.org/10.1037/0003-066X.61.4.271

Carlyle, T. (1869). Heroes and hero-worship (Vol. 12). Chapman and Hall.

Darley, J. M., & Latané´, B. (1968). Bystander intervention in emergencies: Diffusion of responsibility . Journal of Personality and Social Psychology, 8 , 377–383.

Isoz, V. (2020). International System of Scientific Evidence Levels (version 2020).

Petty, R.E. and Cacioppo, J.T. (1986). The Elaboration Likelihood Model of Persuasion. Advances in Experimental Social Psychology, 19 , 123-205. doi: https://doi.org/10.1016/S0065-2601(08)60214-2

Piaget, J. (1956; 1965). The origins of intelligence in children . International Universities Press Inc. New York.

Piaget, J. (1959). The language and thought of the child: Selected works vol. 5. Routledge, London.

Stegenga, J. (2014). Down with the hierarchies. Topoi , 33 (2), 313-322.

Tversky, A., & Kahneman, D. (1973). Availability: A heuristic for judging frequency and probability. Cognitive Psychology, 5 (2), 207–32. https://doi.org/10.1016/0010-0285(73)90033-9

Youyou, W., Stillwell, D., Schwartz, H. A., & Kosinski, M. (2017). Birds of a feather do flock together: Behavior-based personality-assessment method reveals personality similarity among couples and friends. Psychological Science , 28 (3), 276–284. https://doi.org/10.1177/0956797616678187

Apendix: Hierarchy of Evidence in Text Format

• Dave Cornell (PhD) https://helpfulprofessor.com/author/dave-cornell-phd/ 23 Achieved Status Examples
• Dave Cornell (PhD) https://helpfulprofessor.com/author/dave-cornell-phd/ 25 Defense Mechanisms Examples
• Dave Cornell (PhD) https://helpfulprofessor.com/author/dave-cornell-phd/ 15 Theory of Planned Behavior Examples
• Dave Cornell (PhD) https://helpfulprofessor.com/author/dave-cornell-phd/ 18 Adaptive Behavior Examples

• Chris Drew (PhD) https://helpfulprofessor.com/author/chris-drew-phd/ 23 Achieved Status Examples
• Chris Drew (PhD) https://helpfulprofessor.com/author/chris-drew-phd/ 15 Ableism Examples
• Chris Drew (PhD) https://helpfulprofessor.com/author/chris-drew-phd/ 25 Defense Mechanisms Examples
• Chris Drew (PhD) https://helpfulprofessor.com/author/chris-drew-phd/ 15 Theory of Planned Behavior Examples

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Evidence-based practice for effective decision-making

Effective HR decision-making is based on considering the best available evidence combined with critical thinking.

People professionals are faced with complex workplace decisions and need to understand ‘what works’ in order to influence organisational outcomes for the better. 

Evidence-based practice helps them make better, more effective decisions by choosing reliable, trustworthy solutions and being less reliant on outdated received wisdom, fads or superficial quick fixes. 

At the CIPD, we believe this is an important step for the people profession to take: our Profession Map describes a vision of a profession that is principles-led, evidence-based and outcomes-driven. Taking an evidence-based approach to decision-making can have a huge impact on the working lives of people in all sorts of organisations worldwide.

This factsheet outlines what evidence-based practice is and why it is so important, highlighting the four sources of evidence to draw on and combine to ensure the greatest chance of making effective decisions. It then looks to the steps we can take to move towards an evidence-based people profession. 

On this page

• What is evidence-based practice?
• Why is evidence-based practice important?
• What evidence should we use?
• How can we move towards an evidence-based people profession?
• Useful contacts and further reading

At the heart of evidence-based practice is the idea that good decision-making is achieved through critical appraisal of the best available evidence from multiple sources. When we say ‘evidence’, we mean information, facts or data supporting (or contradicting) a claim, assumption or hypothesis. This evidence may come from scientific research, the local organisation, experienced professionals or relevant stakeholders. We use the following definition from CEBMa :

“Evidence-based practice is about making decisions through the conscientious, explicit and judicious use of the best available evidence from multiple sources… to increase the likelihood of a favourable outcome.”

In search of best available evidence

The reasons why evidence-based practice is so important, the principles that underpin it, how it can be followed and how challenges in doing so can be overcome.

Information overload

In their report Evidence-based management: the basic principles , Eric Barends, Denise Rousseau and Rob Briner of CEBMa outline the challenge of biased and unreliable management decisions. 

People professionals face all sorts of contradictory insights and claims about what works and what doesn’t in the workplace. As Daniel Levitin puts it:

"We're assaulted with facts, pseudo facts, jibber-jabber, and rumor, all posing as information. Trying to figure out what you need to know and what you can ignore is exhausting."

While assessing the reliability of evidence becomes more important as the mass of opinion grows, with such a barrage of information, we inevitably use mental shortcuts to make decisions easier and to avoid our brains overloading.

Unfortunately, this means we are prone to biases. Our reports a head for hiring and our minds at work outline the most common of these:

• Authority bias: the tendency to overvalue the opinion of a person or organisation that is seen as an authority
• Conformity bias: the tendency to conform to others in a group, also referred to as 'group think' or 'herd behaviour'
• Confirmation bias: looking to confirm existing beliefs when assessing new information
• Patternicity or the illusion of causality: the tendency to see patterns and assume causal relations by connecting the dots even when there is just random 'noise'.

So-called ‘best practice’

Received wisdom and the notion of ‘best practice’ also creates bias. One organisation may look to another as an example of sound practice and decision-making, without critically evaluating the effectiveness of their actions. And while scientific literature on key issues in the field is vital, there’s a gap between this and the perceptions of practitioners, who are often unaware of the depth of research available.

Cherry-picking evidence

Even when looking at research, we can be naturally biased. We have a tendency to ‘cherry-pick’ research that backs up a perspective or opinion and ignores research that does not, even if it gives stronger evidence on cause-and-effect relationships. This bad habit is hard to avoid – it's even common among academic researchers. So we need approaches that help us determine which research evidence we should trust.

Our ‘insight’ article When the going gets tough, the tough get evidence explains the importance of taking an evidence-based approach to decision making in light of the COVID-19 pandemic. It emphasises and discusses how decision makers can and should become savvy consumers of research.

How can evidence-based practice help?

Our thought leadership article outlines the importance of evidence-based practice in more detail but, essentially, it has three main benefits:

• It ensures that decision-making is based on fact, rather than outdated insights, short-term fads and natural bias.
• It creates a stronger body of knowledge and as a result, a more trusted profession.
• It gives more gravitas to professionals, leads to increased influence on other business leaders and has a more positive impact in work.

The four sources of evidence

The issues above demonstrate the limitations of basing decisions on limited, unreliable evidence. Before making an important decision or introducing a new practice, an evidence-based people professional should start by asking: "What is the available evidence?" As a minimum, people professionals should consider four sources of evidence.

• Scientific literature on people management has become more readily available in recent years, particularly on topics such as the recruitment and selection of personnel, the effect of feedback on performance and the characteristics of effective teams. People professionals’ ability to search for and appraise research for its relevance and trustworthiness is essential.
• Organisational data must be examined as it highlights issues needing a manager’s attention. This data can come externally from customers or clients (customer satisfaction, repeated business), or internally from employees (levels of job satisfaction, retention rates). There’s also the comparison between ‘hard’ evidence, such as turnover rate and productivity levels, and ‘soft’ elements, like perceptions of culture and attitudes towards leadership. Gaining access to organisational data is key to determining causes of problems, and finding and implementing solutions.
• Expertise and judgement of practitioners, managers, consultants and business leaders is important to ensure effective decision-making. This professional knowledge differs from opinion as it’s accumulated over time through reflection on outcomes of similar actions taken in similar contexts. It reflects specialised knowledge acquired through repeated experience of specialised activities.
• Stakeholders, both internal (employees, managers, board members) and external (suppliers, investors, shareholders), may be affected by an organisation’s decisions and their consequences. Their values reflect what they deem important, which in turn affects how they respond to the organisation’s decisions. Acquiring knowledge of their concerns provides a frame of reference for analysing evidence.

Combining the evidence

One very important element of evidence-based practice is collating evidence from different sources. There are six ways – depicted in our infographic below – which will encourage this:

Evidence based practice infographic

• Asking – translating a practical issue or problem into an answerable question.
• Acquiring – systematically searching for and retrieving evidence.
• Appraising – critically judging the trustworthiness and relevance of the evidence.
• Aggregating – weighing and pulling together the evidence.
• Applying – incorporating the evidence into a decision-making process.
• Assessing – evaluating the outcome of the decision taken so as to increase the likelihood.

Through these six steps, practitioners can ensure the quality of evidence is not ignored. Appraisal varies depending on the source of evidence, but generally involves the same questions:

• Where and how is evidence gathered?
• Is it the best evidence available?
• Is it sufficient to reach a conclusion?
• Might it be biased in a particular direction? If so, why?

Evidence-based practice is about using the best available evidence from multiple sources to optimise decisions. Being evidence-based is not a question of looking for ‘proof’, as this is far too elusive. However, we can – and should – prioritise the most trustworthy evidence available. The gains in making better decisions on the ground, strengthening the body of knowledge and becoming a more influential profession are surely worthwhile.

To realise the vision of a people profession that’s genuinely evidence-based, we need to move forward on two fronts. 

First, we need to make sure that the body of professional knowledge is evidence-based – the CIPD’s Evidence review hub is one way in which we are doing this. 

Second, people professionals need to develop capacity in engaging with the best available evidence. Doing this as a non-researcher may feel daunting, but taking small steps towards more evidence-based decisions can make a huge difference. Our thought leadership article outlines a maturity model for being more evidence-based in more detail, but to summarise, we’d encourage people professionals to take the following steps:

• Read research : engage with high-quality research on areas of interest through reading core textbooks and journals that summarise research.
• Collect and analyse organisational data : in the long-term, developing analytical capability should be an aim for the people profession. More immediately, HR leaders should have some knowledge of data-analytics, enough to ask probing questions and make the case for the resources needed for robust measures.
• Review published evidence , including conducting or commissioning short evidence reviews of scientific literature to inform decisions.
• Pilot new practices : evaluate new interventions through applying the same principles used in rigorous cause-and-effect research.
• Share your knowledge : strengthen the body of knowledge by sharing research insights at events or in publications.
• Critical thinking : throughout this process, question assumptions and carefully consider where there are gaps in knowledge.

Developing this sort of capability is a long journey but one that people professionals should aspire to. As the professional body for HR and people development, the CIPD takes an evidence-based view on the future of work – and, importantly, what this means for our profession. By doing this, we can help prepare professionals and employers for what’s coming, while also equipping them to succeed and shape a changing world of work.

Our Profession Map has been developed to do this. It defines the knowledge, behaviours and values which should underpin today’s people profession. It has been developed as an international standard against which an organisation can benchmark its values. At its core are the concepts of being principles-led, evidence-based and outcomes driven. This recognises the importance of using the four forms of evidence in a principled manner to develop positive outcomes for stakeholders. As evidence is often of varying degrees of quality, it’s important that people professionals consider if and how they should incorporate the different types of evidence into their work.

Evidence-based practice is a useful concept for understanding whether practices in HR lead to the desired outcomes, and whether these practices are being used to the best effect. 

Both our guide and thought leadership article offer a detailed, step-by-step approach to using evidence-based practice in your decision making.

All our evidence reviews are featured on our Evidence Hub . For a learning and development perspective, listen to our Evidence-based L&D podcast. There's also Using evidence in HR decision-making: 10 lessons from the COVID-19 crisis , part of our coronavirus webinar series.

Center for Evidence-Based Management (CEBMa)  

ScienceForWork - Evidence-based management  

Books and reports

Barends, E. and Rousseau, D. (2018)  Evidence-based management: how to use evidence to make better organizational decisions . Kogan Page: London

Levitin, D. (2015) The Organized Mind: Thinking Straight in the Age of Information Overload . London: Penguin. 

Randell, G. and Toplis, J. (2014)  Towards organizational fitness: a guide to diagnosis and treatment . London: Gower.

Visit the  CIPD and Kogan Page Bookshop  to see all our priced publications currently in print.

Journal articles

Petticrew, M. and Roberts, H. (2003) Evidence, hierarchies, and typologies: horses for courses . Journal Of Epidemiology And Community Health . Vol 57(7): 527.

Rousseau, D. (2020) Making evidence based-decisions in an uncertain world.  Organizational Dynamics . Vol 49, No 1, January-March. Reviewed in Bitesize research.

Severson, E. (2019) Real-life EBM: what it feels like to lead evidence-based HR.  People + Strategy . Vol 42, No 1, pp22-27.

CIPD members can use our  online journals  to find articles from over 300 journal titles relevant to HR.

Members and  People Management  subscribers can see articles on the  People Management  website.

This factsheet was last updated by Jake Young: Research Associate, CIPD

Jake’s research interests cover a number of workplace topics, notably inclusion and diversity. Jake is heavily involved with CIPD’s evidence reviews, looking at a variety of topics including employee engagement, employee resilience and virtual teams.

Tackling barriers to work today whilst creating inclusive workplaces of tomorrow.

Related content

We all know that being evidence-based helps us make better decisions, but how can we turn this into a reality?

A case study on using evidence-based practice to better understand how to support hybrid workforces

A case study on using evidence-based practice to reinvigorate performance management practices

A case study on using evidence-based practice to review selection processes for promoting police officers

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Distinguishing case study as a research method from case reports as a publication type

The purpose of this editorial is to distinguish between case reports and case studies. In health, case reports are familiar ways of sharing events or efforts of intervening with single patients with previously unreported features. As a qualitative methodology, case study research encompasses a great deal more complexity than a typical case report and often incorporates multiple streams of data combined in creative ways. The depth and richness of case study description helps readers understand the case and whether findings might be applicable beyond that setting.

Single-institution descriptive reports of library activities are often labeled by their authors as “case studies.” By contrast, in health care, single patient retrospective descriptions are published as “case reports.” Both case reports and case studies are valuable to readers and provide a publication opportunity for authors. A previous editorial by Akers and Amos about improving case studies addresses issues that are more common to case reports; for example, not having a review of the literature or being anecdotal, not generalizable, and prone to various types of bias such as positive outcome bias [ 1 ]. However, case study research as a qualitative methodology is pursued for different purposes than generalizability. The authors’ purpose in this editorial is to clearly distinguish between case reports and case studies. We believe that this will assist authors in describing and designating the methodological approach of their publications and help readers appreciate the rigor of well-executed case study research.

Case reports often provide a first exploration of a phenomenon or an opportunity for a first publication by a trainee in the health professions. In health care, case reports are familiar ways of sharing events or efforts of intervening with single patients with previously unreported features. Another type of study categorized as a case report is an “N of 1” study or single-subject clinical trial, which considers an individual patient as the sole unit of observation in a study investigating the efficacy or side effect profiles of different interventions. Entire journals have evolved to publish case reports, which often rely on template structures with limited contextualization or discussion of previous cases. Examples that are indexed in MEDLINE include the American Journal of Case Reports , BMJ Case Reports, Journal of Medical Case Reports, and Journal of Radiology Case Reports . Similar publications appear in veterinary medicine and are indexed in CAB Abstracts, such as Case Reports in Veterinary Medicine and Veterinary Record Case Reports .

As a qualitative methodology, however, case study research encompasses a great deal more complexity than a typical case report and often incorporates multiple streams of data combined in creative ways. Distinctions include the investigator’s definitions and delimitations of the case being studied, the clarity of the role of the investigator, the rigor of gathering and combining evidence about the case, and the contextualization of the findings. Delimitation is a term from qualitative research about setting boundaries to scope the research in a useful way rather than describing the narrow scope as a limitation, as often appears in a discussion section. The depth and richness of description helps readers understand the situation and whether findings from the case are applicable to their settings.

CASE STUDY AS A RESEARCH METHODOLOGY

Case study as a qualitative methodology is an exploration of a time- and space-bound phenomenon. As qualitative research, case studies require much more from their authors who are acting as instruments within the inquiry process. In the case study methodology, a variety of methodological approaches may be employed to explain the complexity of the problem being studied [ 2 , 3 ].

Leading authors diverge in their definitions of case study, but a qualitative research text introduces case study as follows:

Case study research is defined as a qualitative approach in which the investigator explores a real-life, contemporary bounded system (a case) or multiple bound systems (cases) over time, through detailed, in-depth data collection involving multiple sources of information, and reports a case description and case themes. The unit of analysis in the case study might be multiple cases (a multisite study) or a single case (a within-site case study). [ 4 ]

Methodologists writing core texts on case study research include Yin [ 5 ], Stake [ 6 ], and Merriam [ 7 ]. The approaches of these three methodologists have been compared by Yazan, who focused on six areas of methodology: epistemology (beliefs about ways of knowing), definition of cases, design of case studies, and gathering, analysis, and validation of data [ 8 ]. For Yin, case study is a method of empirical inquiry appropriate to determining the “how and why” of phenomena and contributes to understanding phenomena in a holistic and real-life context [ 5 ]. Stake defines a case study as a “well-bounded, specific, complex, and functioning thing” [ 6 ], while Merriam views “the case as a thing, a single entity, a unit around which there are boundaries” [ 7 ].

Case studies are ways to explain, describe, or explore phenomena. Comments from a quantitative perspective about case studies lacking rigor and generalizability fail to consider the purpose of the case study and how what is learned from a case study is put into practice. Rigor in case studies comes from the research design and its components, which Yin outlines as (a) the study’s questions, (b) the study’s propositions, (c) the unit of analysis, (d) the logic linking the data to propositions, and (e) the criteria for interpreting the findings [ 5 ]. Case studies should also provide multiple sources of data, a case study database, and a clear chain of evidence among the questions asked, the data collected, and the conclusions drawn [ 5 ].

Sources of evidence for case studies include interviews, documentation, archival records, direct observations, participant-observation, and physical artifacts. One of the most important sources for data in qualitative case study research is the interview [ 2 , 3 ]. In addition to interviews, documents and archival records can be gathered to corroborate and enhance the findings of the study. To understand the phenomenon or the conditions that created it, direct observations can serve as another source of evidence and can be conducted throughout the study. These can include the use of formal and informal protocols as a participant inside the case or an external or passive observer outside of the case [ 5 ]. Lastly, physical artifacts can be observed and collected as a form of evidence. With these multiple potential sources of evidence, the study methodology includes gathering data, sense-making, and triangulating multiple streams of data. Figure 1 shows an example in which data used for the case started with a pilot study to provide additional context to guide more in-depth data collection and analysis with participants.

Key sources of data for a sample case study

VARIATIONS ON CASE STUDY METHODOLOGY

Case study methodology is evolving and regularly reinterpreted. Comparative or multiple case studies are used as a tool for synthesizing information across time and space to research the impact of policy and practice in various fields of social research [ 9 ]. Because case study research is in-depth and intensive, there have been efforts to simplify the method or select useful components of cases for focused analysis. Micro-case study is a term that is occasionally used to describe research on micro-level cases [ 10 ]. These are cases that occur in a brief time frame, occur in a confined setting, and are simple and straightforward in nature. A micro-level case describes a clear problem of interest. Reporting is very brief and about specific points. The lack of complexity in the case description makes obvious the “lesson” that is inherent in the case; although no definitive “solution” is necessarily forthcoming, making the case useful for discussion. A micro-case write-up can be distinguished from a case report by its focus on briefly reporting specific features of a case or cases to analyze or learn from those features.

DATABASE INDEXING OF CASE REPORTS AND CASE STUDIES

Disciplines such as education, psychology, sociology, political science, and social work regularly publish rich case studies that are relevant to particular areas of health librarianship. Case reports and case studies have been defined as publication types or subject terms by several databases that are relevant to librarian authors: MEDLINE, PsycINFO, CINAHL, and ERIC. Library, Information Science & Technology Abstracts (LISTA) does not have a subject term or publication type related to cases, despite many being included in the database. Whereas “Case Reports” are the main term used by MEDLINE’s Medical Subject Headings (MeSH) and PsycINFO’s thesaurus, CINAHL and ERIC use “Case Studies.”

Case reports in MEDLINE and PsycINFO focus on clinical case documentation. In MeSH, “Case Reports” as a publication type is specific to “clinical presentations that may be followed by evaluative studies that eventually lead to a diagnosis” [ 11 ]. “Case Histories,” “Case Studies,” and “Case Study” are all entry terms mapping to “Case Reports”; however, guidance to indexers suggests that “Case Reports” should not be applied to institutional case reports and refers to the heading “Organizational Case Studies,” which is defined as “descriptions and evaluations of specific health care organizations” [ 12 ].

PsycINFO’s subject term “Case Report” is “used in records discussing issues involved in the process of conducting exploratory studies of single or multiple clinical cases.” The Methodology index offers clinical and non-clinical entries. “Clinical Case Study” is defined as “case reports that include disorder, diagnosis, and clinical treatment for individuals with mental or medical illnesses,” whereas “Non-clinical Case Study” is a “document consisting of non-clinical or organizational case examples of the concepts being researched or studied. The setting is always non-clinical and does not include treatment-related environments” [ 13 ].

Both CINAHL and ERIC acknowledge the depth of analysis in case study methodology. The CINAHL scope note for the thesaurus term “Case Studies” distinguishes between the document and the methodology, though both use the same term: “a review of a particular condition, disease, or administrative problem. Also, a research method that involves an in-depth analysis of an individual, group, institution, or other social unit. For material that contains a case study, search for document type: case study.” The ERIC scope note for the thesaurus term “Case Studies” is simple: “detailed analyses, usually focusing on a particular problem of an individual, group, or organization” [ 14 ].

PUBLICATION OF CASE STUDY RESEARCH IN LIBRARIANSHIP

We call your attention to a few examples published as case studies in health sciences librarianship to consider how their characteristics fit with the preceding definitions of case reports or case study research. All present some characteristics of case study research, but their treatment of the research questions, richness of description, and analytic strategies vary in depth and, therefore, diverge at some level from the qualitative case study research approach. This divergence, particularly in richness of description and analysis, may have been constrained by the publication requirements.

As one example, a case study by Janke and Rush documented a time- and context-bound collaboration involving a librarian and a nursing faculty member [ 15 ]. Three objectives were stated: (1) describing their experience of working together on an interprofessional research team, (2) evaluating the value of the librarian role from librarian and faculty member perspectives, and (3) relating findings to existing literature. Elements that signal the qualitative nature of this case study are that the authors were the research participants and their use of the term “evaluation” is reflection on their experience. This reads like a case study that could have been enriched by including other types of data gathered from others engaging with this team to broaden the understanding of the collaboration.

As another example, the description of the academic context is one of the most salient components of the case study written by Clairoux et al., which had the objectives of (1) describing the library instruction offered and learning assessments used at a single health sciences library and (2) discussing the positive outcomes of instruction in that setting [ 16 ]. The authors focus on sharing what the institution has done more than explaining why this institution is an exemplar to explore a focused question or understand the phenomenon of library instruction. However, like a case study, the analysis brings together several streams of data including course attendance, online material page views, and some discussion of results from surveys. This paper reads somewhat in between an institutional case report and a case study.

The final example is a single author reporting on a personal experience of creating and executing the role of research informationist for a National Institutes of Health (NIH)–funded research team [ 17 ]. There is a thoughtful review of the informationist literature and detailed descriptions of the institutional context and the process of gaining access to and participating in the new role. However, the motivating question in the abstract does not seem to be fully addressed through analysis from either the reflective perspective of the author as the research participant or consideration of other streams of data from those involved in the informationist experience. The publication reads more like a case report about this informationist’s experience than a case study that explores the research informationist experience through the selection of this case.

All of these publications are well written and useful for their intended audiences, but in general, they are much shorter and much less rich in depth than case studies published in social sciences research. It may be that the authors have been constrained by word counts or page limits. For example, the submission category for Case Studies in the Journal of the Medical Library Association (JMLA) limited them to 3,000 words and defined them as “articles describing the process of developing, implementing, and evaluating a new service, program, or initiative, typically in a single institution or through a single collaborative effort” [ 18 ]. This definition’s focus on novelty and description sounds much more like the definition of case report than the in-depth, detailed investigation of a time- and space-bound problem that is often examined through case study research.

Problem-focused or question-driven case study research would benefit from the space provided for Original Investigations that employ any type of quantitative or qualitative method of analysis. One of the best examples in the JMLA of an in-depth multiple case study that was authored by a librarian who published the findings from her doctoral dissertation represented all the elements of a case study. In eight pages, she provided a theoretical basis for the research question, a pilot study, and a multiple case design, including integrated data from interviews and focus groups [ 19 ].

We have distinguished between case reports and case studies primarily to assist librarians who are new to research and critical appraisal of case study methodology to recognize the features that authors use to describe and designate the methodological approaches of their publications. For researchers who are new to case research methodology and are interested in learning more, Hancock and Algozzine provide a guide [ 20 ].

We hope that JMLA readers appreciate the rigor of well-executed case study research. We believe that distinguishing between descriptive case reports and analytic case studies in the journal’s submission categories will allow the depth of case study methodology to increase. We also hope that authors feel encouraged to pursue submitting relevant case studies or case reports for future publication.

Editor’s note: In response to this invited editorial, the Journal of the Medical Library Association will consider manuscripts employing rigorous qualitative case study methodology to be Original Investigations (fewer than 5,000 words), whereas manuscripts describing the process of developing, implementing, and assessing a new service, program, or initiative—typically in a single institution or through a single collaborative effort—will be considered to be Case Reports (formerly known as Case Studies; fewer than 3,000 words).

Evidence Based Practice

• 1. Ask: PICO(T) Question
• 2. Align: Levels of Evidence
• 3a. Acquire: Resource Types
• 3b. Acquire: Searching
• 4. Appraise

Primary vs. Secondary Sources

• Qualitative and Quantitative Sources
• Managing References

Sources are considered primary, secondary, or tertiary depending on the originality of the information presented and their proximity or how close they are to the source of information. This distinction can differ between subjects and disciplines.

In the sciences, research findings may be communicated informally between researchers through email, presented at conferences (primary source), and then, possibly, published as a journal article or technical report (primary source). Once published, the information may be commented on by other researchers (secondary sources), and/or professionally indexed in a database (secondary sources). Later the information may be summarized into an encyclopedic or reference book format (tertiary sources). Source

Primary Sources

A primary source in science is a document or record that reports on a study, experiment, trial or research project. Primary sources are usually written by the person(s) who did the research, conducted the study, or ran the experiment, and include hypothesis, methodology, and results.

Primary Sources include:

• Pilot/prospective studies
• Cohort studies
• Survey research
• Case studies
• Lab notebooks
• Clinical trials and randomized clinical trials/RCTs
• Dissertations

Secondary Sources

Secondary sources list, summarize, compare, and evaluate primary information and studies so as to draw conclusions on or present current state of knowledge in a discipline or subject. Sources may include a bibliography which may direct you back to the primary research reported in the article.

Secondary Sources include:

• reviews, systematic reviews, meta-analysis
• newsletters and professional news sources
• practice guidelines & standards
• clinical care notes
• patient education Information
• government & legal Information
• entries in nursing or medical encyclopedias Source

More on Systematic Reviews and Meta-Analysis

Systematic reviews – Systematic reviews are best for answering single questions (eg, the effectiveness of tight glucose control on microvascular complications of diabetes). They are more scientifically structured than traditional reviews, being explicit about how the authors attempted to find all relevant articles, judge the scientific quality of each study, and weigh evidence from multiple studies with conflicting results. These reviews pay particular attention to including all strong research, whether or not it has been published, to avoid publication bias (positive studies are preferentially published). Source

Meta-analysis -- Meta-analysis, which is commonly included in systematic reviews, is a statistical method that quantitatively combines the results from different studies. It can be used to provide an overall estimate of the net benefit or harm of an intervention, even when these effects may not have been apparent in the individual studies [ 9 ]. Meta-analysis can also provide an overall quantitative estimate of other parameters such as diagnostic accuracy, incidence, or prevalence. Source

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