MIXED POISSON REGRESSION-MODELS WITH COVARIATE DEPENDENT RATES

This paper studies a class of Poisson mixture models that includes, co variates in rates. This model contains Poisson regression and independ ent Poisson mixtures as special cases. Estimation methods based on the EM and quasi-Newton algorithms, properties of these estimates, a mode l selection procedure, residual analysis, and goodness-of-fit test are discussed. A Monte Carlo study investigates implementation and model choice issues. This methodology is used to analyze seizure frequency a nd Ames salmonella assay data.