Mann Whitney U Test Formula. A mann whitney u test sometimes called the wilcoxon rank sum test is used to compare the differences between two samples when the sample distributions are not normally distributed and the sample sizes are small n 30 it is considered to be the nonparametric equivalent to the two sample t test. Tails 1 or 2 default.
Mwtest r1 r2 tails ties cont p value of the mann whitney u test for the samples contained in ranges r1 and r2 using the normal approximation. Is approximately distributed as a normal distribution with a mean of 0 and a standard deviation of 1 n 0 1. The mann whitney test is based on a comparison of every observation x.
The mann whitney test is based on a comparison of every observation x.
Displaystyle y and both samples independent of each other. If cont true default a continuity correction is applied. Either of these two formulas are valid for the mann whitney u test. So for example one might compare the speed at which two different groups of people can run 100 metres where one group has trained for six weeks and the other has not.
