The recent literature on preferential trade agreements (PTAs) emphasizes the distinction between the extensive and intensive margins. What has been missing is the distinction between tariff and non-tariff changes under PTAs. Tariff reduction is a quintessential feature of PTAs. But member...

In a seminal paper, Helpman et al. (2008) demonstrate that accounting for self-selection and firm heterogeneity is crucial for obtaining unbiased estimates in the gravity equation. In this paper, we show how this insight helps solve the trade elasticity puzzle that, hitherto, trade elasticity...