Performing a Three-Way ANOVA Through SPSS Point and Click
The data in Table 8.12 consist of blood pressure scores for 72 participants. Three categorical independent variables: the presence and absence of biofeedback (biofeed), drug X, Y, or Z (drug), and diet absent or present (diet) have beenfactorially combined to form a 2 x 3 x 2 design where each person contributes one blood pressure score to one of the 12 different experimental conditions. For this example, there are 6 participants in each group.
First, the omnibus tests of interest will be computed to determine if there are differences among the groups on the mean level of blood pressure. Table 8.14 illustrates the results replicated here.
1. Click Analyze, then General Linear Model, then Univariate.
2. Place the dependent variable (bp) in the Dependent Variable box and the group factors (biofeed, drug, and diet) in the Fixed Factor(s) box. Then click OK.
As of this writing, more specific tests of group mean comparisons in the context of multifactor ANOVAs can only be carried out directly in SPSS with the MANOVA procedure through syntax. Please refer to the SPSS syntax for these analyses.