The COUNTREG procedure provides regression models in which the dependent variable takes nonnegative integer count values. The COUNTREG procedure supports the following features:
Poisson regression
Conway-Maxwell-Poisson regression
negative binomial regression with quadratic and linear variance functions
zero-inflated Poisson (ZIP) regression
zero-inflated Conway-Maxwell-Poisson regression
zero-inflated negative binomial (ZINB) regression
fixed- and random-effects Poisson panel data models
fixed- and random-effects NB (negative binomial) panel data models
variable selection
Bayesian estimation and inference, including diagnostic plots