NEW DEVELOPMENTS IN PAIRWISE MULTIPLE COMPARISONS - SOME POWERFUL AND PRACTICABLE PROCEDURES

Recent developments in procedures for conducting pairwise multiple comparisons of means prompted an empirical investigation of several competing techniques. Monte Carlo results revealed that the newer multistage sequential procedures maintain their familywise Type I error probabilities while exhibiting power that is superior to the traditional competitors. Of all procedures examined, the modified Peritz (1970) procedure (Seaman, Levin, Serlin, & Franke, 1990) is generally the most powerful according to all definitions of power. At the same time, when computational ease and convenience are taken into consideration, Hayter's (1986) procedure should be regarded as a viable alternative. Beyond pairwise comparisons of means, the versatile Holm (1979) procedure and its modifications (Shaffer, 1986) are very attractive insofar as they represent simple, yet powerful, data-analytic tools for behavioral researchers.