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 range distribution, denoted \(q\). The Games-Howell test is performed on the ranked variables similar to other nonparametric tests. Since the Games-Howell test does not rely on equal variances and sample sizes, it is often recommended over other approaches such as Tukey’s test.
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