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Document type:
Zeitschriftenaufsatz 
Author(s):
Czado, C., Erhardt, V., Min, A. and Wagner, S. 
Title:
Zero-inflated generalized Poisson models with regression effects on the mean, dispersion and zero-inflation level applied to patent outsourcing rates 
Abstract:
This paper focuses on an extension of zero-inflated generalized Poisson (ZIGP) regression models for count data. We discuss generalized Poisson (GP) models where dispersion is modelled by an additional model parameter. Moreover, zero-inflated models in which overdispersion is assumed to be caused by an excessive number of zeros are discussed. In addition to ZIGP models considered by several authors, we now allow for regression on the overdispersion and zero-inflation parameters. Consequently,...    »
 
Keywords:
maximum likelihood estimator; overdispersion; patent outsourcing; Vuong test; zero-inflated generalized Poisson regression; zero-inflation 
Journal title:
Statistical Modelling 
Year:
2007 
Journal volume:
Journal issue:
Pages contribution:
125-153 
Reviewed:
ja 
Language:
en 
Semester:
SS 07 
Format:
Text