Chapter 10, Table 5: Performing a Mixed Model ANOVA Through SPSS Syntax

The data in Table 10.5 consist of simulated ACT scores from 40 participants where 10 participants were selected from each of four schools. It is assumed that the schools are randomly selected from a population of schools in America in order to generalize the results found. Two schools (and thus, 20 participants) are randomly assigned to the computer-based ACT training program, while the other two schools are randomly assigned to the standard paper-and-pencil program in order to assess the effectiveness of these different types of programs.

The primary hypothesis of interest is whether the standard paper-and-pencil and computer-based ACT training programs differ in effectiveness. The following procedure generates the output to assess this hypothesis. It is important to note that, as of this writing, SPSS through the point and click procedure does not provide the correct statistical test for the main effect of the random factor in this situation as the denominator is incorrectly specified as the mean square for the interaction instead of the mean square error. The following syntax does provide the correct statistical tests in a two-factor mixed model design, keeping in mind that the correct statistical test for the fixed effect is found at the end of the output under the “Custom Hypothesis Tests” section.

At this point, click Run and then All to obtain the results.