The Mann-Whitney U test (or Rank-Sum test) is used to compare two groups of samples to see if there is a significant difference.
Unlike the unpaired t-test, it is non-parametric and does not require the data to be normally distributed, or even continuous. It can also distinguish between groups with the same mean but different distributions.
After selecting Mann-Whitney U from the menu, simply enter the values for each sample. Biostats Calculator will compare the distributions of the groups and perform a hypothesis test to determine whether there is a statistically significant difference.
Biostats Calculator reports: