Gravity and Heterogeneous Trade Cost Elasticities
提出一个灵活的引力方程，预测贸易成本弹性在国家和国家对之间变化，并应用于货币联盟、贸易协定和WTO成员等变量，发现平均上促进贸易但存在显著异质性，薄关系弹性大，厚关系弹性小甚至为零。
Abstract How do trade costs affect international trade? This paper offers a new approach. We rely on a flexible gravity equation that predicts variable trade cost elasticities, both across and within country pairs. We apply this framework to popular trade cost variables such as currency unions, trade agreements and World Trade Organization membership. While we estimate that these variables are associated with increased bilateral trade on average, we find substantial heterogeneity. Consistent with the predictions of our framework, trade cost effects are strong for ‘thin’ bilateral relationships characterised by small import shares, and weak or even zero for ‘thick’ relationships.