人口结构变迁与经常账目失衡

世界范围内持续多年的经常账目失衡并不鲜见，以往研究多关注汇率和净出口的关系，而忽视了经常账目余额的另外一种属性——本国在外国的储蓄。本文尝试从人口结构变迁的角度对这一问题给出新的解释。本文通过构建包括幼年抚养比和老年抚养比的世代交替模型，理论分析和预测了：幼年抚养比上升会降低储蓄率、增加投资率，从而减少经常账目余额；而老年抚养比下降会提高储蓄率，增加经常账目余额；试图填补人口结构对经常账目影响的理论空白。接下来，本文利用1990年至2011年全球110个国家的强平衡面板数据进行实证分析，在静态和动态模型下均得到了与理论预测相一致的稳健结果。根据实证结果进行定量分析，本文发现中国抚养比的变化可以解释1990年至2007年间经常账目余额占GDP比重16.6%的变动。

Demographic Transition and Current Account Imbalances

Since 1994 China has witnessed current account surplus for 18 consecutive years. Previous research mostly focuses on the relationship between exchange rate and net export, but ignores another attribute of the current account balance--domestic savings in foreign countries. This paper intends to provide an explanation to the persistent current account imbalance from the perspective of demographic transition. Youth dependency ratio and elderly dependency ratio are introduced to a three generation overlapping model. The model suggests that the rise of youth dependency ratio decreases total saving rate and increases investment rate. It thus reduces current account balance. On the other hand, the rise of elderly dependency ratio increases total saving rate. It thus boosts current account balance. The theory is tested empirically with a panel data set from 110 countries during 1990 to 2011. With both static and dynamic regressions, we obtain robust evidences that support the theoretic predictions. We find that 16. 6% of current account balance variation between 1990 and 2007 could be explained by demographic changes in China.