Correction procedures (STATA commands NBSTRAT and GNBSTRAT) are applied to simultaneously account for zero-truncation, endogenous stratification, and overdispersion, and also consider heterogeneity in the overdispersion parameter. Their effect is shown on welfare estimates from previous studies, confirming that the routines perform the appropriate correction and only when endogenous stratification is expected.
Martínez-Espiñeira, Roberto and Hilbe, Joseph M.
"Effect on Recreation Benefit Estimates from Correcting for On-Site Sampling Biases and Heterogeneous Trip Overdispersion in Count Data Recreation Demand Models (STATA),"
Journal of Modern Applied Statistical Methods:
1, Article 29.
Available at: http://digitalcommons.wayne.edu/jmasm/vol7/iss1/29