STEPWISE AND SIMULTANEOUS MULTIPLE COMPARISON PROCEDURES OF REPEATED-MEASURES MEANS

Stepwise multiple comparison procedures (MCPs) for repeated measures' means based on the methods of Hayter (1986), Hochberg (1988), Peritz (1970), Ryan (1960)-Welsch (1977a), Shaffer (1979, 1986), and Welsch (1977a) were compared for their overall familywise rates of Type I error when multisample sphericity and multivariate normality were not satisfied. Robust stepwise procedures were identified by Keselman, Keselman, and Shaffer (1991) with respect to three definitions of power. On average, Welsch's (1977a) step-up procedure was found to be the most powerful MCP.