The group covariates for a SURPH probability are defined in much the same way as the main effect parameters, except that:
Below is an example of the group covariate dialog window for a study with 2 group covariates ("middle" and "late"), and 2 periods. It shows the default setting of all zeroes, indicating that no group covariates are included in the model (see Release-recapture notes).
As with the main effects dialog window , periods with the same number share a common parameter for a given covariate. Note, however, that parameters are not shared across covariates; each covariate has it's own set of parameters.