Resumen de Estimation and testing of binomial and beta-binomial regression models with and without zero inflation

James W. Hardin, Joseph M. Hilbe

• We present new Stata commands for carrying out several regression commands suitable for binomial outcomes. The zib command extends Stata�s binreg command to allow zero inflation. The betabin command fits binomial regression models allowing for beta overdispersion, and the zibbin command fits a beta-binomial regression model with zero inflation. All the new commands allow the specification of links within the glm command�s collection for both outcome and zero inflation. The zero-inflated commands optionally calculate a Vuong test comparing the zero-inflated model with the nonzero-inflated model, and the zibbin command optionally includes a likelihood-ratio test of the overdispersion parameter.