Nonparametric statistics are used when our data are measured on a nominal or ordinal scale of measurement. Chi-square statistics and their modifications (e.g., McNemar Test) are used for nominal data. All other nonparametric statistics are appropriate when data are measured on an ordinal scale of measurement. The nonparametric statistics that we learned in class are listed below.

In order to choose among these tests, we must next determine the number of samples in the study design and the relationship between samples.