The chapter discusses tests for comparing two sets of data that are not normally distributed. The Mann–Whitney test is used for unpaired data, while the Wilcoxon signed-rank test is for paired data. The Wilcoxon Sign test is for paired data with a binary outcome. These tests are alternatives to the t-test and are helpful when data does not follow a normal distribution. SPSS software can be used to analyze the results of these nonparametric tests.