These fixed effects are in addition to the primary time and treatment effects, so do not specify any effects confounded with those. The effects can include any mixture of class variables (as specified in the Additional Class Variables above) or continuous covariates .
If you specify more than one fixed effects, you must separate the effects with spaces . For example, assuming A and B are listed as Class Variables, entering A B in the text field specifies variables A and B as main fixed effects.
To specify interactions between effect, enter an asterisk ( * ) between the effects. For example, assuming A and B are listed as Class Variables, entering A B A*B specifies variables A , B , and the interaction between A and B as fixed effects and constructs a two-way ANOVA model.
A vertical bar ( | ) can be used to create main effects and interactions. For example, entering A|B is the same as entering A B A*B .