| Parametric (Not suitable) | Nonparametric (Suitable) | |---------------------------|--------------------------| | Pearson correlation | Spearman’s rho | | Independent t-test | Mann-Whitney U | | Paired t-test | Wilcoxon signed-rank | | One-way ANOVA | Kruskal-Wallis H | | Repeated-measures ANOVA | Friedman test | A. Compare two independent groups Test: Mann-Whitney U Example: Compare pain scores (ordinal) between Treatment vs. Placebo groups.
Ordinal data has a clear order/ranking but unequal or unknown intervals between values.