  We revisit simple and powerful methods for multiple pairwise comparisons that
can be used in designs with three groups. We argue that the proper choice of
method should be determined by the assessment which of the comparisons are
considered primary and which are secondary, as determined by subject-matter
considerations. We review four different methods that are simple to use with
any standard software, but are substantially more powerful than frequently-used
methods such as an ANOVA test followed by Tukey's method.
