Mann-Whitney test

The Mann-Whitney test is a nonparametric test used to see if two sets of data have the same distribution, for example, error scores for expert and novice users of an application. It is the nonparametric equivalent of Student's t-test. The Mann-Whitney test is a form of order statistics; if the two datasets (say A and B) have the same distribution, then when all the values from the two distributions are sorted in order, the pattern of As and Bs should be random.

The Wilcoxon rank sum test is effectively the same as Mann-Whitney, but uses a slightly different calculation over the order statistics.

For paired data, say pre- and post-test scores, use the Wilcoxon signed rank test, which is a the nonparametric equivalent of a paired t test