贸易弹性的长期与短期

中文摘要

当各国调整最惠国（MFN）关税时，按照最惠国条款开展贸易的伙伴国会经历可合理视为外生的关税变化。利用这一变化，我们采用局部投影法估计短期和长期的贸易弹性。研究发现，不含关税的贸易流量弹性在短期为−0.76，在长期约为−2。我们的长期估计值小于文献中的典型估计值，而且需要7至10年才能收敛至长期水平。这意味着：（i）贸易带来的福利收益很高；（ii）出口调整成本具有相当强的凸性。（JEL C51、F13、F14）

Abstract

When countries change most favored nation (MFN) tariffs, partners that trade on MFN terms experience plausibly exogenous tariff changes. Using this variation, we estimate the trade elasticity at short and long horizons with local projections. We find that the elasticity of tariff-exclusive trade flows is −0.76 in the short run, and approximately −2 in the long run. Our long-run estimates are smaller than typical in the literature, and it takes 7 to10 years to converge to the long run, implying that (i) the welfare gains from trade are high and (ii) there are substantial convexities in the costs of adjusting exports. (JEL C51, F13, F14)