Chapter 14, Table 8: One-Within One-Between

(Multivariate Approach) via SPSS Syntax

For the hypothetical data contained in Table 14.8, a perceptual psychologist is interested in age differences (“young” and “old”) in reaction time on a perceptual task. In addition, the psychologist is also interested in the effect of angle (zero degrees off center and eight degrees off center). The question of interest is to see if there are is a main effect of age, a main effect of angle, and an interaction between the two.

The analysis of the data given in Table 14.8 begins by making use of the GLM procedure. As before, we specify the within-subjects factor under GLM, however here we also have a BY statement. Variables to the right of the BY statement specify the between subject effects, in this case group. Because we have two levels of the within-subject factor angle, we include /WSFACTOR with angle 2 to the right of it. Group is included on the /DESIGN line (because it is a between subject factor) and angle is included on the /WSDESIGN line.

After clicking Run and then All the results will be produced. Note that, as before, for the within-subject effects both the univariate and the multivariate approaches are performed by default. Here we are only concerned with the multivariate approach. The results obtained match those given in the text on pages 707 (for the between-subject main effect), 709 (for the interaction), and 712 (for the within-subject main effect).