Parameters | Expression Parameters | Covariates

Use this text box to specify variables to use as additional effects beside the corresponding data values from the tall Input SAS Data Set in the model.

To specify interactions between effect, type an asterisk (*) between the effects. For example, assuming A and B are listed as class variables, typing A B A*B specifies variables A and B, and the interaction between A and B as effects.

A vertical bar (|) can be used to create main effects and interactions. For example, typing A|B is the same as typing A B A*B.