A. Colin Cameron and Pravin K. Trivedi
"Essentials of Count Data Regression"
in Badi H. Baltagi ed., A Companion to Theoretical Econometrics, 2001, pp. 331-348, Blackwell, Oxford (U.K.)
Count data models are presented for cross-section data in Sections 2 to 4. Section 2 details the Poisson regression model. This model is often too restrictive and other, more commonly-used, fully parametric count models are presented in Section 3. Less-used alternative parametric approaches for counts, such as discrete choice models and duration models, are also presented in this section. The partially parametric approach of modeling the conditional mean and conditional variance is detailed in Section 4. Extensions to other types of data, notably time series, multivariate and panel data, are given in Section 5. In Section 6 practical recommendations are provided. For pedagogical reasons the Poisson regression model for cross-section data is presented in some detail. The other models, many superior to Poisson, are presented in less detail for space reasons.