Games-Howell Test for Post-Hoc Analysis

The Games-Howell post-hoc test is another nonparametric approach to compare combinations of groups or treatments. Although rather similar to Tukey’s test in its formulation, the Games-Howell test does not assume equal variances and sample sizes. The test was designed based on Welch’s degrees of freedom correction and uses Tukey’s studentized...

Post-Hoc Analysis with Tukey’s Test

In a previous example, ANOVA (Analysis of Variance) was performed to test a hypothesis concerning more than two groups. Although ANOVA is a powerful and useful parametric approach to analyzing approximately normally distributed data with more than two groups (referred to as ‘treatments’), it does not provide any deeper insights...