twexp and twgravity: Estimating exponential regression models with two-way fixed effects

Abstract

We introduce the commands twexp and twgravity that implement the estimators developed in Jochmans (2017) for exponential regression models with two-way fixed effects. twexp is applicable to generic n x m panel data. twgravity is written for the special case where the data is a cross-section on dyadic interactions between n agents. A prime example of the latter is cross-sectional bilateral trade data, where the model of interest is a gravity equation with importer and exporter effects. Both twexp and twgravity can deal with data where n and m are large, that is, the case of many fixed effects. They make use of Mata and are very fast to execute.