EFFECT name=effect-type (variables </ options>);
The EFFECT statement enables you to construct special collections of columns for design matrices. These collections are referred to as constructed effects to distinguish them from the usual model effects that are formed from continuous or classification variables, as discussed in the section GLM Parameterization of Classification Variables and Effects in Chapter 20, Shared Concepts and Topics.
You can specify the following effect-types:
specifies a collection effect that defines one or more variables as a single effect that has multiple degrees of freedom. The variables in a collection are considered as a unit for purposes of estimation and inference.
specifies a multimember classification effect whose levels are determined by one or more variables that appear in a CLASS statement.
specifies a multivariate polynomial effect in the specified numeric variables.
specifies a regression spline effect whose columns are univariate spline expansions of one or more variables. A spline expansion replaces the original variable with an expanded or larger set of new variables.
For more information about the syntax of these effect-types and how columns of constructed effects are computed, see the section EFFECT Statement in Chapter 20, Shared Concepts and Topics.