Chapter 11, Table 5: Repeated Measures (Univariate Approach) via SPSS Syntax

For the present data set, 12 children were each observed four times over an 18 month period. The dependent variable is the age-normed general cognitive score on the McCarthy Scales of Children’s Abilities. Interest is to determine if the children were sampled from a population where growth in cognitive ability is more rapid or less rapid than average.

The analysis of the data proceeds by making use of the GLM procedure where a within subject factor is specified (/WSFACTOR).

Notice that the four levels of the repeated factor (months) are specified under GLM. Also notice that 4 is specified after months on the /WSFACTOR line, telling SPSS that there are four levels of the within subject factor for months.

At this point clicking Run and then All will yield the results of the analysis (given on page 539). Note that there are several analyses performed and output by default. The one that is currently of interest is the Sphericity Assumed result contained in the Tests of Within Subjects Effects output box. Although each of the four results contained in the Tests of Within Subjects Effects output box are the same in this instance, in general this will not be the case, as is explained in the second half of Chapter 11. Note that the adjusted F tests (which will soon be of interest) are given in the Tests of Within Subjects Effects output box.