Educational researchers often use multiple statistical tests in their research studies and program evaluations. When multiple statistical tests are conducted, the chance that Type I errors may be committed increases. Thus, the researchers are faced with the task of adjusting the alpha levels for their individual statistical tests in order to keep the overall alpha value at a reasonable level. A three-step procedure is presented that can be used to adjust the alpha levels of the individual statistical tests. This procedure requires researchers to: (1) identify the appropriate conceptual unit for the error rate (pairwise, experimentwise, and familywise); (2) determine the number and nature of tests contained in that error rate unit; and (3) apply a Bonferroni-type adjustment procedure to the various statistical tests contained in each error rate unit. This three-step adjustment procedure emphasizes that it is the obligation of the researchers to make logical decisions, not mechanical ones, when adjusting Type I error rates for multiple statistical tests. (Contains 20 references.) (Author/SLD)

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