Use the text field to specify random effects by which to model the covariance structure of the response variable .Random effects are typically comprised of class variables and their interactions. Be sure to specify any class variables in the Additional Class Variables field above.Do not repeat any effects here that are confounded with Time , Treatment , or any effect specified in the Additional Fixed Effects field.Commonly used random effects are SITEID (for multi-center trials) and STUDYID (for data assembled from multiple studies).
If you specify more than one random effect, then you must separate the effects with spaces . For example, assuming A and B are listed as Class Variables, typing A B in the text field specifies variables A and B as random effects.