Using the gravity equation to differentiate among alternative theories of trade: another look

This study compares two alternative approaches-the traditional ordinary least square (OLS) and the Poisson Quasi Maximum Likelihood (PQML) procedures-to estimation of the home market effects for the heterogeneous, the reference priced and the homogeneous goods in the gravity model derived in Feenstra et al. ( 2001 ). Despite our findings that the PQML estimation results oftentimes (significantly) differ from those obtained by the OLS procedure, both estimation procedures largely lead to the qualitatively similar conclusions on the existence of the home market effect for the different types of goods with several exceptions.