Use the Compare Means options to perform multiple comparisons of group means. All of these methods use pooled variance estimates for the means. Each Compare Means option adds comparison circles next to the plot and specific reports to the report window. For details about comparison circles, see Using Comparison Circles.
Computes individual pairwise comparisons using Student’s ttests. If you make many pairwise tests, there is no protection across the inferences. Therefore, the alphasize (Type I error rate) across the hypothesis tests is higher than that for individual tests. See Each Pair, Student’s t.


Shows a test that is sized for all differences among the means. This is the Tukey or TukeyKramer HSD (honestly significant difference) test. (Tukey 1953, Kramer 1956). This test is an exact alphalevel test if the sample sizes are the same, and conservative if the sample sizes are different (Hayter 1984). See All Pairs, Tukey HSD.


Note: If you have specified a Block column, then the multiple comparison methods are performed on data that has been adjusted for the Block means.