We develop a model of firms' auditor choices when presented with a heterogeneous group of investors. We show that firms' auditor choices in equilibrium depend on the composition of investors in the market. The signaling effect of choosing a high-quality auditor exists only when there is at least a certain proportion of sophisticated investors. If there is a sufficiently high proportion of sophisticated investors, then all firms will choose high-quality auditors. We also show that the overall audit quality in the market increases with an increasing proportion of sophisticated investors. When the audit market is differentiated and investors are heterogeneous, an increase in the penalty for firms that receive a qualified opinion will lead to a decrease in the overall audit quality in the market. Our conclusions remain valid even after taking audit fees, auditor quality change, and firm heterogeneity into consideration.

本文利用长期面板数据,对玉米被引入中国后,对明清农民起义发生率的影响进行了定量分析。分析结果显示,玉米播种时间和农民起义发生率存在U形关系:短期内,玉米的引种确实有助于降低气候灾害引发的农民起义的发生率,但这种效应是逐渐减弱的。到清朝中后期,玉米播种时间更久的地区甚至更易受水旱灾害危害,进而更易爆发农民起义。这说明了以玉米为代表的美洲作物的引种并未能让中国像欧洲国家那样摆脱"气候—治乱循环"。 

This paper explores whether educational attainment has a cognitive reserve capacity in elder life. Using pilot data from the China Health and Retirement Longitudinal Study (CHARLS), we examined the impact of education on cognitive abilities at old ages. OLS results showed that respondents who completed primary school obtained 18.2 percent higher scores on cognitive tests than those who did not. We then constructed an instrumental variable (IV) by leveraging China's Great Famine of 1959–1961 as a natural experiment to estimate the causal effect of education on cognition. Two-stage least squares (2SLS) results provided sound evidence that completing primary school significantly increases cognition scores, especially in episode memory, by almost 20 percent on average. Moreover, Regression Discontinuity (RD) analysis provides further evidence for the causal interpretation, and shows that the effects are different for the different measures of cognition we explored. Our results also show that the Great Famine can result in long-term health consequences through the pathway of losing educational opportunities other than through the pathway of nutrition deprivation.

人口结构是否会影响国际贸易?一方面,高劳动人口比例会使出口国产出增加,从而增加出口;另一方面,高劳动人口比例也会给进口国带来更多的劳动收入,从而增加进口。本文利用176个国家从1970年到2006年的大样本面板数据,并控制多边阻力等因素,在引入劳动人口比之后,对贸易引力方程的回归分析支持了如下理论预测:贸易国的劳动人口比例上升会增加双边贸易流;出口国(进口国)平均劳动人口比上升1%,出口(进口)会上升至少3%(2%)。这一发现对于理解人口大国(如中印)或贸易大国(如中美)的贸易具有重要的理论和现实意义。