Research on tests for scale equality have focused exclusively on an overall test statistic and have not examined procedures for identifying specific differences in multiple group designs. The present study compares four contrast analysis procedures for scale differences in the single factor four-group design: (1) Tukey HSD; (2) Kramer-Tukey; (3) Games-Howell; and (4) Dunnett T-3. Two data transformations are considered under several combinations of variance difference, sample sizes, and distributional forms. The data for the study were generated using the Statistical Analysis System computing package. The results indicate that no single transformation or analysis procedure is uniformly superior in controlling the family-wise error rate or in statistical power. The relationship between sample size and variances is a major factor in selecting a contrast analysis procedure. Adopting a multiple analysis strategy is recommended. Four tables show comparisons in these methods.

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