Regression models for count data based on the negative binomial(p) distribution

• Autores: James W. Hardin, Joseph M. Hilbe
• Localización: The Stata journal, ISSN 1536-867X, Vol. 14, Nº. 2, 2014, págs. 280-291
• Idioma: inglés
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• Resumen

  • We present new Stata commands for estimating several regression models suitable for analyzing overdispersed count outcomes. The nbregp command nests the dispersion(constant) and dispersion(mean) versions of Stata�s nbreg command in a model for negative binomial(p) regression. The zignbreg command extends Stata�s gnbreg command for zero inflation, and the zinbregp command fits a negative binomial(p) regression model with zero inflation. The new commands for zero-inflated models allow specification of links within the glm command�s collection for the Bernoulli model of zero inflation. These commands will optionally calculate a Vuong test, which compares the zero-inflated model with the nonzeroinflated model.