Using computer simulated data, the Type I error rate and statistical power were empirically estimated for several pairwise multiple comparison strategies for situations where population variances differ. Focus was on comparing modified Bonferroni procedures with Dunnett's solutions, and determining whether or not J. P. Shaffer's suggestion of…

Research investigations on teacher training effects have focused almost exclusively on differences between group means. The present paper suggests that several interesting and important research questions might be answered by examining student variability both within and between classrooms. Student variability might be considered as an outcome to…