Restricted accessResearch articleFirst published online 1974-10
Comparison of Tukey's T-Method and Scheffé's S-Method for Various Numbers of All Possible Differences of Averages Contrasts Under Violation of Assumptions
Empirical .05 and .01 rates of Type I error were compared for the Tukey and Scheffé multiple comparison techniques. The experimentwise error rate was defined over five sets of the all possible 25 differences of averages contrasts. The robustness of the Tukey and Scheffé statistics was not only related to the type of assumption violation, but also to the sets containing different numbers of contrasts. The Tukey method could be judged as robust a statistic as the Scheffé method.
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