Abstract
A limitation of the Tukey HSD procedure for multiple comparison has been the requirement of equal number of observations for each group. Three approximation techniques have been suggested when the group sizes are unequal. Each of these techniques was empirically analyzed to determine its effect on TypeI error. Two of the considered variables, average group size and differences in group size, caused differing actual probabilities of TypeI error. One of the three techniques (Kramer's) consistently provided actual probabilities in close agreement with corresponding nominal probabilities.
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Smith, R.A. The effect of unequal group size on Tukey's HSD procedure. Psychometrika 36, 31–34 (1971). https://doi.org/10.1007/BF02291420
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DOI: https://doi.org/10.1007/BF02291420