RE: Model building question

From: "kai wu" kaiwu77@yahoo.com Subject: RE: [NMusers] Model building question Date: Mon, February 28, 2005 9:04 am Atul, What I did was :model as two different populations at two occasion first, compared their bayesian estimators, and regressed on the baseline change to have some idea. Then I pooled two as one population. As you suggested, testing BOV would be the first step. If single BOV and none of combinations of BOV on parameters was significant, they would be disregarded in the following model building process. However, I found that if I go the other way around: build the model first, then introduce BOV to the final model, the results were quite different in terms of parameter estimator and objective function value. Or should I consider BOVs and the baseline change as potential covariates at the same level, use either forward or backward procedure to build the model? Kai Wu Department of Pharmaceutics University of Florida Gainesville, Fl Office phone #: 352-846-2730