Trading Partners and Trading Volumes:Implementing the Helpman-Melitz-Rubinstein Model Empirically
Helpman, Melitz, and Rubinstein (2008)�HMR�present a rich theoretical model to study the determinants of bilateral trade flows across countries. The model is then empirically implemented through a two-stage estimation procedure. This note seeks to clarify some econometric aspects of the estimation approach used by HMR and explore the consequences of possible departures from the maintained distributional assumptions.