Kruskal-Wallis and Mann-Whitney U test

This episode of the podcast discusses the Kruskal-Wallis test, which is a non-parametric alternative to the one-way ANOVA test. It is used to compare multiple independent groups when the data does not meet the assumptions of the ANOVA. The test is appropriate for ordinal or non-normal data, and it compares the ranks of the data instead The podcast talks about before and after studies which is a type of pre-post design in quasi-experimental research. It is used when randomization is not possible or when there is no control group. The purpose is to measure the effects of an intervention or exposure on a population. The quality of the study can be assessed by looking at sample selection, confounders, regression to the mean, attrition bias, and outcome variables. The Mann-Whitney U test is a nonparametric test.