Mann–Whitney U test

The Mann–Whitney U test is a way to compare two sets of data and find out if they're different from each other. The test compares two sets by looking at how many times each value appears in the two sets. It's used when you want to look at data that isn't normally distributed, like when one set is really big and the other is really small. For example, if you wanted to compare the heights of people from China and New Zealand, you might use the Mann–Whitney U test, since the population of New Zealand is much smaller than China's.