A good rule of thumb is that the number of comparisons (c) be no larger than the degrees of freedom (df). This test is very conservative and its power quickly declines as the c increases. It is appropriate when the number of comparisons (c = number of comparisons = k(k-1))/2) exceeds the number of degrees of freedom (df) between groups (df = k-1). This test does not require the overall ANOVA to be significant. It is not appropriate for additional means. This test is appropriate when you have 3 means to compare. This test is the most liberal of all Post Hoc tests and its critical t for significance is not affected by the number of groups. Post Hoc tests that do not assume equal variancesįisher's LSD (Least Significant Different) R-E-G-W Q (Ryan-Einot-Gabriel-Welsch range test)

R-E-G-W F (Ryan-Einot-Gabriel-Welsch F test) Scheffe (confidence intervals that are fairly wide) Tukey’s b (AKA, Tukey’s WSD (Wholly Significant Difference))īonferroni (don't use with 5 groups or greater)ĭunnett (compares a control group to the other groups without comparing the other groups to each other) Tukey’s HSD (honestly significant difference) test Post Hoc tests that assume equal variance Multiple Comparison Tests AND Range Tests Pairwise multiple comparisons test the difference between each pair of means, and yield a matrix where asterisks indicate significantly different group means at an alpha level of 0.05” (SPSS, Inc.). Range tests identify homogeneous subsets of means that are not different from each other. “Once you have determined that differences exist among the means, post hoc range tests and pairwise multiple comparisons can determine which means differ. Note: The editor is unsure of the source of this material.

Sigmaplot 11 do not test bonferroni