人口结构是怎样影响经常账户不平衡的?——以第二次世界大战为工具变量的经验证据

How Does Demographic Structure Affect Current Account Imbalance?——Empirical Evidence from the Instrumental Variable Estimation of WWII

本文利用第二次世界大战资料构造了人口结构的工具变量,通过2005—2012年165个国家的跨国面板数据考察了人口结构与经常账户结余的因果关系。发现人口抚养比对一国的经常账户结余有显著的正向影响,而且在利用工具变量处理了内生性问题之后,这个影响在程度上更大,显著性也更强了。进一步考察发现,人口抚养比提高导致的"预防性储蓄"动机的上升抵消了"生命周期理论"的效应,使得人口结构对于储蓄率没有稳健的显著影响;而由于"谨慎性投资"效应,使得人口抚养比的上升显著降低了一国的企业家精神和投资率。因而,人口抚养比拉大了国内储蓄与投资的差额,形成了经常账户结余。这些发现预示,在中国人口抚养比面临拐点,未来可能持续上升的情况下,中国的经常账户盈余也会持续存在。

This paper identifies the causal relationship between dependent ratio and current account surplus with a national level panel data about 165 countries in the period of 2005 to 2012. The main contribution of our research is utilizing WWlI as an instrumental variable to tackle the endogeneity problem of demographic structure in previous studies. We find that dependent ratio has a positive effect on current account surplus, which is even magnified after using IV. We further find that increased dependent ratio enhances the motivation of precautionary saving, which offsets the ＂life-cycle＂ motive to save less and renders insignificant the effect of dependent ratio on saving rates. Besides, by decreasing the marginal rate of return of investment and by hampering social entrepreneurship, a heightened dependent ratio significantly reduces investment ratio of a society. Our result indicates that, with a persistent augmentation of dependent ratio in the future, China may experience prolonged current account surplus