CONTRAST ANALYSIS IN REPEATED MEASURES ANALYSIS OF VARIANCE DESIGNS - A SAS IMPLEMENTATION

The use of contrast analysis has been emphasized as an alternative to the two-stage sequence of omnibus F test followed by post-hoc pairwise comparisons. Instead, user contrasts tailored to the research can be formulated. Expressing each cell in a contrast in terms of the parameters of the means model is the key to determine the coefficients of the contrast. A three-way ANOVA with repeated measures on two factors is used to illustrate the technique. The code for the SAS Procedure GLM provides examples.