Linear regression - Hypothesis testing
by Marco Taboga , PhD
This lecture discusses how to perform tests of hypotheses about the coefficients of a linear regression model estimated by ordinary least squares (OLS).
Table of contents
Normal vs non-normal model
The linear regression model, matrix notation, tests of hypothesis in the normal linear regression model, test of a restriction on a single coefficient (t test), test of a set of linear restrictions (f test), tests based on maximum likelihood procedures (wald, lagrange multiplier, likelihood ratio), tests of hypothesis when the ols estimator is asymptotically normal, test of a restriction on a single coefficient (z test), test of a set of linear restrictions (chi-square test), learn more about regression analysis.
The lecture is divided in two parts:
in the first part, we discuss hypothesis testing in the normal linear regression model , in which the OLS estimator of the coefficients has a normal distribution conditional on the matrix of regressors;
in the second part, we show how to carry out hypothesis tests in linear regression analyses where the hypothesis of normality holds only in large samples (i.e., the OLS estimator can be proved to be asymptotically normal).
We also denote:
We now explain how to derive tests about the coefficients of the normal linear regression model.
It can be proved (see the lecture about the normal linear regression model ) that the assumption of conditional normality implies that:
How the acceptance region is determined depends not only on the desired size of the test , but also on whether the test is:
one-tailed (only one of the two things, i.e., either smaller or larger, is possible).
For more details on how to determine the acceptance region, see the glossary entry on critical values .
The F test is one-tailed .
A critical value in the right tail of the F distribution is chosen so as to achieve the desired size of the test.
Then, the null hypothesis is rejected if the F statistics is larger than the critical value.
In this section we explain how to perform hypothesis tests about the coefficients of a linear regression model when the OLS estimator is asymptotically normal.
As we have shown in the lecture on the properties of the OLS estimator , in several cases (i.e., under different sets of assumptions) it can be proved that:
These two properties are used to derive the asymptotic distribution of the test statistics used in hypothesis testing.
The test can be either one-tailed or two-tailed . The same comments made for the t-test apply here.
Like the F test, also the Chi-square test is usually one-tailed .
The desired size of the test is achieved by appropriately choosing a critical value in the right tail of the Chi-square distribution.
The null is rejected if the Chi-square statistics is larger than the critical value.
Want to learn more about regression analysis? Here are some suggestions:
R squared of a linear regression ;
Gauss-Markov theorem ;
Generalized Least Squares ;
Multicollinearity ;
Dummy variables ;
Selection of linear regression models
Partitioned regression ;
Ridge regression .
How to cite
Please cite as:
Taboga, Marco (2021). "Linear regression - Hypothesis testing", Lectures on probability theory and mathematical statistics. Kindle Direct Publishing. Online appendix. https://www.statlect.com/fundamentals-of-statistics/linear-regression-hypothesis-testing.
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COMMENTS
The hypotheses are: H0: β1 = 0. H1: β1 ≠ 0. The null hypothesis of a two-tailed test states that there is not a linear relationship between x and y. The alternative hypothesis of a two-tailed test states that there is a significant linear relationship between x and y.
APA Formatted Summary Example. A simple regression was used to test the hypothesis that hours of sleep would predict quiz scores. Consistent with the hypothesis, hours of sleep was a significant predictor of quiz scores, F(1, 8) = 70.54 F (1, 8) = 70.54, p p < .05. Approximately 89.8% of the variance in quiz scores was accounted for by variance ...
We will use Hypothesis Testing on β₁ for the same. Steps to Perform Hypothesis testing: Set the Hypothesis; Set the Significance Level, Criteria for a decision; Compute the test statistics...
As in simple linear regression, under the null hypothesis t 0 = βˆ j seˆ(βˆ j) ∼ t n−p−1. We reject H 0 if |t 0| > t n−p−1,1−α/2. This is a partial test because βˆ j depends on all of the other predictors x i, i 6= j that are in the model. Thus, this is a test of the contribution of x j given the other predictors in the model.
Linear regression - Hypothesis testing. by Marco Taboga, PhD. This lecture discusses how to perform tests of hypotheses about the coefficients of a linear regression model estimated by ordinary least squares (OLS).
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