We introduce two new Stata commands for the estimation of an or- dered response model with sample selection. The opsel command uses a standard maximum-likelihood approach to fit a parametric specification of the model where errors are assumed to follow a bivariate Gaussian distribution. The...

Nonrandom sample selection may render estimated treatment effects biased even if assignment of treatment is purely random. Lee (2009, Review of Economic Studies, 76: 1071–1102) proposes an estimator for treatment-effect bounds that limit the possible range of the treatment effect. In this...

This paper presents code for fitting a FIML endogenous switching Poisson count model for cross-sectional data in Stata 7: the espoisson command. The Poisson process depends on an unobserved heterogeneity term, ; a set of explanatory variables, x; and an endogenous dummy, d. The endogenous dummy...

Studying behavior in economics, sociology, and statistics often involves fitting models in which the response variable depends on a dummy variable- also known as a regime-switch variable- or in which the response variable is observed only if a particular selection condition is met. In either...