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What does a Tukey post-hoc test show?
The Tukey Test (or Tukey procedure), also called Tukey’s Honest Significant Difference test, is a post-hoc test based on the studentized range distribution. An ANOVA test can tell you if your results are significant overall, but it won’t tell you exactly where those differences lie.
What is post-hoc test used for?
Post hoc (“after this” in Latin) tests are used to uncover specific differences between three or more group means when an analysis of variance (ANOVA) F test is significant.
When do you use the Tukey post hoc test?
The term “pairwise” means we only want to compare two group means at a time. For example, suppose we have three groups – A, B, C. The Tukey post-hoc test would allow us to make the following pairwise comparisons: Note that for k groups, there are a total of k(k-1)/2 possible pairwise comparisons.
Which is post hoc multiple comparison test should I use?
Tukey in SPSS is in reality Tukey-Cramer test that is equivalent to the Tukey test if experiment is balanced but allow to use it if experiment is not balanced. Sheffè is a test with very low power, so is too much protective, more than Bonferroni or Sidak.
When to use the Scheffe post hoc test?
Note that for k groups, there are a total of k(k-1)/2 possible pairwise comparisons. The Scheffe post-hoc test should be used when you would like to make all possible contrasts between group means. This test allows you to compare more than just two means at once, unlike the Tukey post-hoc test.
What’s the difference between Tukey and paired t tests?
The Tukey results are based on a model having an underlying assumption that the error variance is the same for every pairwise comparison. The paired t tests are not based on that model, and each paired test is based on a different subset of the data whereas the original model is fitted to all of the data.