The paired t-test is useful for analyzing the same set of items that were measured under two different conditions, differences in measurements made on the same subject before and after a treatment, or differences between two treatments given to the same subject.
For example, the manager of a fitness facility uses a paired t-test to determine whether a group of participants improved their fitness after an 8-week program. If there is a difference in fitness measurements before and after the program, the manager can use the confidence interval to determine whether the difference is practically significant.
To perform a paired t-test, choose.
If you have two samples of independent observations, use 2-Sample t instead. For more information, go to How are dependent and independent samples different?.