Nonparametric Statistics

Distribution-free tests are hypothesis tests that make no assumptions about the probability distributions of the variables being assessed.

The sign test can be used to test the hypothesis that there is "no difference in medians" between the continuous distributions of two random variables.

Two notable nonparametric methods of making inferences about single populations are bootstrapping and the Anderson–Darling test.

Nonparametric independent samples tests include Spearman's and the Kendall tau rank correlation coefficients, the Kruskal–Wallis ANOVA, and the runs test.

McNemar's test is applied to $2 \times 2$ contingency tables with matched pairs of subjects to determine whether the row and column marginal frequencies are equal.

Nonparametric methods using randomized block design include Cochran's $Q$ test and Friedman's test.

A rank correlation is any of several statistics that measure the relationship between rankings.