CONSISTENT ESTIMATION OF ZERO-INFLATED COUNT MODELS
Version of Record online: 24 MAY 2012
Copyright © 2012 John Wiley & Sons, Ltd.
Volume 22, Issue 6, pages 673–686, June 2013
How to Cite
Staub, K. E. and Winkelmann, R. (2013), CONSISTENT ESTIMATION OF ZERO-INFLATED COUNT MODELS. Health Econ., 22: 673–686. doi: 10.1002/hec.2844
- Issue online: 7 MAY 2013
- Version of Record online: 24 MAY 2012
- Manuscript Accepted: 24 APR 2012
- Manuscript Revised: 23 MAR 2012
- Manuscript Received: 8 AUG 2011
- excess zeros;
- unobserved heterogeneity;
Applications of zero-inflated count data models have proliferated in health economics. However, zero-inflated Poisson or zero-inflated negative binomial maximum likelihood estimators are not robust to misspecification. This article proposes Poisson quasi-likelihood estimators as an alternative. These estimators are consistent in the presence of excess zeros without having to specify the full distribution. The advantages of the Poisson quasi-likelihood approach are illustrated in a series of Monte Carlo simulations and in an application to the demand for health services. Copyright © 2012 John Wiley & Sons, Ltd.