The t-test is a frequently used statistical procedure that compares the means of two groups. There are two versions of the test based on whether the two groups are matched or not matched. Matched groups (also known as pair

The t-test is a frequently used statistical procedure that compares the means of two groups. There are two versions of the test based on whether the two groups are matched or not matched. Matched groups (also known as paired groups or samples) share many common characteristics, whereas unmatched groups (or independent groups or samples) do not. You must be able to identify which version of the t-test should be used in a given situation.