贸易三元边际与国民福利——基于多产品异质性企业视角的模型分析

Trade Ternary Margins and National Welfare:Mathematical Analysis from the Perspective of Multiproduct Heterogeneous Firm Model

本文基于多产品异质性企业模型,分析了贸易三元边际的多边福利效应。该模型允许企业内产品种类发生变化,能够对两种主流的贸易扩展边际概念(企业与产品)进行合并建模。研究发现,对于出口国而言,贸易扩展边际是促进其国民福利的主要原因;对于进口国而言,贸易集约数量边际促进其国民福利,但贸易集约价格边际会阻碍其国民福利。此外,本文探讨了上述福利效应的影响因素,并引入“进入边际”进行模型分析。这些结论对我国未来的贸易政策选择具有参考意义。

The relationship between trade and welfare is a long-term topic in international economics.We construct a multiproduct heterogeneous firm model that could unify the different ternary margins concepts.This model allows dynamic changes in product categories within the firms.And we conduct a multilateral welfare analysis on the trade margins.For exporting countries,the extensive margin is the main reason to promote their welfare.For importing countries,the intensive quantity margin promotes their welfare,but the intensive price margin hinders their welfare.Furthermore,we discuss the influencing factors of these welfare effects,and we introduce"entrance margin"for model analysis.These conclusions have reference value for China's future trade policy choices.