Under Review

Pairwise Comparisons Using Ranks in the One-Way Model

Multiple Comparisons; Familywise Error Rate; Pairwise Comparisons.

Cite as:

Dennis Boos and Siyu Duan (2019). Pairwise Comparisons Using Ranks in the One-Way Model. RESEARCHERS.ONE, https://www.researchers.one/article/2019-05-2.


The Wilcoxon Rank Sum is a very competitive robust alternative to the two-sample t-test when the underlying data have tails longer than the normal distribution. Extending to the one-way model with k independent samples, the Kruskal-Wallis rank test is a competitive alternative to the usual F for testing if there are any location differences. However, these positives for rank methods do not extend as readily to methods for making all pairwise comparisons used to reveal where the differences in location may exist. We demonstrate via examples and simulation that rank methods can have a dramatic loss in power compared to the standard Tukey-Kramer method of normal linear models even for non-normal data.