May 2021
Beginner
306 pages
6h 20m
English
When you want to compare means in a study where there are three or more groups, you cannot use multiple t tests. In the old days (even before my time!), if you had three groups (let’s call them A, B, and C), you might perform t tests between each pair of means (A versus B, A versus C, and B versus C). With four groups, the situation gets more complicated; you would need six t tests (A versus B, A versus C, A versus D, B versus C, B versus D, and C versus D). Even though no one does multiple t tests anymore, it is important to understand the underlying reason why this is not statistically sound.
Suppose you are comparing four groups and performing six t tests. Also, suppose that the null hypothesis ...