Two by Two Factorial Design via SPSS Point and Click
The following data is a generalization of the blood pressure data given in Table 7.1 (as there are now three, rather than two, levels of the drug factor). In addition to assessing the likelihood of there being a biofeedback or a drug main effect, the interaction is explicitly taken into consideration. The results replicate those given in Table 7.7.
1. Rather than making use of the One-Way ANOVA procedure, it is necessary to use a more general procedure, namely that of the Univariate procedure under the General Linear Model Category (Click Analyze, then General Linear Model, then Univariate). At this point score is moved into the Dependent Variable box while feedback and drug and both moved into the Fixed Factor(s) box.
2. At this point clicking OK will produce the results of the two-by-three ANOVA given in Table 7.7.
Note: Because the Univariate procedure is a generalization of the One-Way ANOVA procedure, it too can be used to perform a one-way ANOVA. The advantages of using the One-Way procedure for one-way designs, however, comes from the additional options (e.g., contrasts and additional statistics) uniquely available from the One-Way menu.