COMMENT ABOUT THE MANN-WHITNEY U

The Mann-Whitney U test, a nonparametric test, is often used as a substitute for the t test, a parametric test. This test is used when the t test's assumptions appear to be in doubt ” for example, when the shape of the distribution does not appear to be normal and the level of measurement is ordinal. The Mann-Whitney U is an easy-to-apply nonparametric test.