This paper suggests a simple specification test to check the adequacy of the assumptions made about the distribution of individual effects in models where these unobservable random variables are integrated out by quadrature methods. Because the proposed test checks the specification of the...

Helpman, Melitz, and Rubinstein (2008)HMRpresent 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...