“一带一路”倡议促进“设施联通”的政策效应评估——基于双重差分的研究

Evaluation of policy effects of“the Belt and Road”initiative promoting“facility connectivity”-A research based on difference-in-difference

"一带一路"倡议着力于基础设施建设以实现"设施联通"进而"贸易畅通",是否在"设施联通"上真正取得进展至关重要,因此需要进行细致的政策效应评估。但以往相关研究大都利用两组两期的标准双重差分(difference-in-difference, DID)估计框架和双向固定效应回归方法,去估计"一带一路"的政策效应,因此可能存在估计偏误。对此,利用物流绩效指数测度"设施联通"程度,根据各国加入"一带一路"倡议时间有先后及先后加入国家间存在实质性差异的现实情况,采用了多组多期的DID估计框架,并利用Callaway等针对该框架提出的改进方法来估计加入倡议对"设施联通"的政策效应。研究发现:加入倡议有助于各组别物流绩效的提升,且提升效应在各组别间呈现明显异质性。将各组别处理效应加总后则显示出较强的处理时期选择效应和动态效应;将物流绩效指数分解为6个子项目后,加入倡议对各子项目也有较强的正面效应。本研究为"一带一路"基础设施建设的政策效应评估提供了全新的方法和思路。

“The Belt and Road”initiative focuses on infrastructure construction to achieve“facility connectivity”prior to“unimpeded trade”.Whether or not real progress is made on“facility connectivity”is essential,thus requiring a detailed policy effect assessment.However,most of the previous researches used two sets of two-stage standard difference-in-difference(DID)estimation framework and two-way fixed-effect regression method to estimate“the Belt and Road”policy effects,likely to produce estimation errors.This study drew on the logistics performance index to measure the degree of“facility connectivity”,and according to the actual situation in which countries joined“the Belt and Road”initiative in the sequence of time and substantial differences exist among those countries,successively adopted multiple sets of multi-period DID estimation framework coupled with a new approach of Callaway and Sant’Anna(2019)tailored to this framework,in order to estimate the policy effects of joining the initiative on“facility connectivity”.It is found that:(1)Joining the initiative helps to improve the logistics performance of each group,and the improvement effect shows obvious heterogeneity among the groups.The sum of the treatment effects of each group shows a strong choice effect and dynamic effect during the treatment period;(2)The logistics performance index is decomposed into six sub-projects,and joining the initiative also has a strong positive effect on each sub-project.This research provides new methods and ideas for evaluation of policy effects of“the Belt and Road”infrastructure construction.