ERROR RATES FOR MULTIPLE COMPARISON METHODS - SOME EVIDENCE CONCERNING FREQUENCY OF ERRONEOUS CONCLUSIONS

7 methods currently used for paired comparisons among all group means following analysis of variance were tested for sensitivity to violation of stated requirements. The t-test methods and the Duncan multiple range test were found to produce far more Type I errors under null conditions than is generally acceptable. The methods of H. Scheffe and J. W. Tukey produced the fewest Type I errors and are least susceptible to violation of requirements. Type II error rates for all methods were generated. The appropriate choice of error rate and multiple comparison method is discussed. (3l ref.) (PsycINFO Database Record (c) 2006 APA, all rights reserved). © 1969 American Psychological Association.