U statistic

The U statistic is a measure used in a statistical test called the Mann-Whitney U test, which compares two groups to see if they differ significantly. It ranks all data points from both groups together, then analyzes how the rankings are distributed between the groups. A low or high U value indicates that one group tends to have higher or lower scores than the other, suggesting a difference in their distributions. This test is useful when data do not follow a normal distribution or when dealing with small sample sizes. It provides a way to assess if two groups are statistically different based on their ranks.