U-statistic

A U-statistic is a type of statistic used in non-parametric statistical inference, particularly in estimating population parameters and testing hypotheses. It is designed to provide a way to estimate the value of a functional of a distribution based on a sample. U-statistics are particularly useful because they have desirable properties such as being asymptotically unbiased and having an asymptotic normal distribution. The general form of a U-statistic is constructed from a symmetric kernel function.