Table : TABLE 18-1. Parametric and Nonparametric Partners Most parametric hypothesis tests have at least one equivalent nonparametric alternative. Here, all the parametric tests call for scale dependent variables, and their nonparametric counterparts all call for ordinal dependent variables.

Design	Parametric Test	Nonparametric Test
Association between two variables	Pearson correlation coefficient	Spearman rank-order correlation coefficient
Two groups; within-groups design	Paired-samples t test	Wilcoxon signed-rank test
Two groups; between-groups design	Independent-samples t test	Mann–Whitney U test
More than two groups; between-groups design	One-way between-groups ANOVA	Kruskal–Wallis H test