ABSTRACT
Many researchers use analysis of variance (ANOVA; Rutherford, 2001; Weiss, 2006) when analyzing their data. Table 1.1 contains an example of a data matrix that can be analyzed with ANOVA. The table contains the scores on the dependent variable y for ten persons from four groups labeled 1 through 4. A typical analysis consists of two steps (let µj denote the population mean of group j for j = 1, . . . , 4):
1. Test H0 : µ1 = µ2 = µ3 = µ4, that is, all four means are equal (“nothing is going on”), against Ha : not H0, that is, not all four means are equal (“something is going on but I do not know what”). If this test favors Ha, continue with the second step.
