APA Dictionary of Psychology

in a factorial design with a variable of interest having more than two levels, a procedure in which the data obtained from each level of the variable are compared separately to the data from every other level. For example, if a researcher is assessing the differences in student achievement resulting from three different types of content presentation, statistical tests would be used to evaluate the different outcomes of each pair of content methods (i.e., Method 1 and Method 2, 1 and 3, and 2 and 3). Dunnett’s multiple comparison test, Tukey’s honestly significant difference test, and the Newman–Keuls multiple comparion test all involve pairwise comparisons. See also multiple comparisons.