Nonparametric tests are used when we don't know the exact shape of the data's distribution. The Wilcoxon-Mann-Whitney test is a popular nonparametric test for comparing groups. This review looks at whether this test is fair or biased when estimating the center of a distribution. The researchers found that the Wilcoxon-Mann-Whitney test is unbiased for estimating the center of a distribution. This means it gives accurate results even when the data doesn't follow a specific pattern.