U-statistics

nonparametric test of the null hypothesis that, for randomly picked values X and Y from 2 populations, Pr(X>Y)=Pr(Y>X)

non-parametric statistical hypothesis test used to compare two related samples to assess whether their population mean ranks differ

statistics computed from a sample of data

In statistical theory, a U-statistic is a class of statistics defined as the average over the application of a given function applied to all tuples of a fixed size. The letter "U" stands for unbiased. In elementary statistics, U-statistics arise naturally in producing minimum-variance unbiased estimators.