The GLMPOWER Procedure

The MODEL statement serves two basic purposes:

• The dependents specify scenarios for the cell means.

• The independents specify the independent effects.

The independents can involve classification variables, continuous variables, or both. You can include main effects and interactions by using the effects notation of PROC GLM; see the section Specification of Effects in Chapter 41, The GLM Procedure for further details. For any model effect involving classification variables (interactions as well as main effects), the number of levels cannot exceed 32,767. If no independent effects are specified, only an intercept term is fit. The MODEL statement must appear before the POWER statement if the EFFECTS option is used in the POWER statement.

You can account for covariates in the model by using the NCOVARIATES= option and either the CORRXY= or PROPVARREDUCTION= option in the POWER statement.

Each dependent variable refers to a set of surmised cell means in the exemplary data set (named by the DATA= option in the PROC GLMPOWER statement). These cell means are response means for all of the subject profiles. Multiple dependent variables correspond to multiple scenarios for these cell means. All models are univariate; the GLMPOWER procedure currently does not support multivariate analyses.

The MODEL statement is required. You can specify only one MODEL statement.