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.