Chapter 7, Table 23: Nonorthogonal Factorial Designs via SPSS Syntax

The following data represent the relative effectiveness of three forms of psychotherapy for alleviating depression. Fifteen individuals were randomly assigned to one of three groups. After the fact, these individuals where placed into one of three categories based on the severity of their depression. Thus, this data set represents a 3 by 3 nonorthogonal factorial design with post hoc blocking.

As before with factorial ANOVAs in SPSS syntax, this analysis makes use of the UNIANOVA procedure. What is important to notice here is the /METHOD=SSTYPE() option must specify the desired type of sums of squares. For illustrative purposes, we have included the necessary syntax to replicate everything given in Table 7.25. It is important to notice the bottom two UNIANOVA statements. They both specify Type I sums of squares, however the entry of the main effects on the /DESIGN line is reversed. The first Type I sums of squares statement (third overall) corresponds to the “Type I—B entered first” summary while the second Type I sums of squares statement (the last one) corresponds to the “Type I—A entered first” summary.

At this point clicking Run and then All will yield the results from each of the four ways of analyzing the data given in Table 7.23 and summarized in Table 7.25.