Fixed Effects Regression Methods for Longitudinal Data Using SAS

3.8. Summary

In this chapter we've seen how the fixed effects methods developed for continuous response variables in chapter 2 can be extended to categorical response variables. Most of the chapter focused on regression models for dichotomous responses. When there are just two dichotomous observations for each individual, a fixed effects regression model can be estimated by (a) discarding all cases that have the same values on the two response variables, (b) recoding all time-varying explanatory variables as difference scores, and (c) fitting a conventional logistic regression model to one of the response variables. This is a form of conditional maximum likelihood.

We then considered the more general case where individuals may have more than ...