All Pairwise Comparisons among Means: Tukey's HSD Procedure (2 of 2)

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The critical value of ts is determined from the distribution of the studentized range. The number of means in the experiment is used in the determination of the critical value, and this critical value is used for all comparisons among means. Typically, the largest mean is compared with the smallest mean first. If that difference is not significant, no other comparisons will be significant either, so the computations for these comparisons can be skipped.

The Tukey HSD procedure keeps the EER at the specified significance level. This is a great advantage. This advantage comes at a cost, however: the Tukey HSD is less powerful than other methods of testing all pairwise comparisons.


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