Multi-level event history analysis for a sibling design: the choice of predictor variables

The chapter by Dronkers and Hox presents an interesting multi-level event history analysis of divorce risks. The sibling design gives excellent opportunities for studying the similarity between brothers and sisters in the risks of divorce. Various discussion points are raised, all of which bear in some way upon the choice of predictor variables in the multi-level logistic regression. Questions are posed about the level of detail of modeling time trends; about the fact that sampling weights are a function of number of siblings; and about the inclusion in the fixed part of the model of the fraction of previously divorced siblings, which is correlated with the family-level random intercept.