中文目錄

1.社交媒體與心理健康
2.經(jīng)濟(jì)學(xué)研究中的實(shí)證策略
3.經(jīng)濟(jì)學(xué)研究中的因果推斷
4.退出 Vs 發(fā)聲
5.金融系統(tǒng)管理的中國模式
6.中國專利激增的真實(shí)影響

1.Social Media and Mental Health（AER2022）

We provide quasi-experimental estimates of the impact of social media on mental health by leveraging a unique natural experiment: the staggered introduction of Facebook across US colleges. Our analysis couples data on student mental health around the years of Facebook's expansion with a generalized difference-in-differences empirical strategy. We find that the rollout of Facebook at a college had a negative impact on student mental health. It also increased the likelihood with which students reported experiencing impairments to academic performance due to poor mental health. Additional evidence on mechanisms suggests the results are due to Facebook fostering unfavorable social comparisons.

2.Empirical Strategies in Economics: Illuminating the Path From Cause to Effect（ECTA2022）

The view that empirical strategies in economics should be transparent and credible now goes almost without saying. By revealing for whom particular instrumental variables (IV) estimates are valid, the local average treatment effects (LATE) framework helped make this so. This lecture uses empirical examples, mostly involving effects of charter and exam school attendance, to illustrate the value of the LATE framework for causal inference. LATE distinguishes independence conditions satisfied by random assignment from more controversial exclusion restrictions. A surprising exclusion restriction is shown to explain why enrollment at Chicago exam schools reduces student achievement. I also make two broader points: IV exclusion restrictions formalize commitment to clear and consistent explanations of reduced-form causal effects; the credibility revolution in applied econometrics owes at least as much to compelling empirical analyses as to methodological insights.

3.Causality in Econometrics: Choice vs Chance（ECTA2022）

This essay describes the evolution and recent convergence of two methodological approaches to causal inference. The first one, in statistics, started with the analysis and design of randomized experiments. The second, in econometrics, focused on settings with economic agents making optimal choices. I argue that the local average treatment effects framework facilitated the recent convergence by making key assumptions transparent and intelligible to scholars in many fields. Looking ahead, I discuss recent developments in causal inference that combine the same transparency and relevance.

4.Exit versus Voice（JPE2022）

We study the relative effectiveness of exit (divestment and boycott) and voice (engagement) strategies in a world where companies generate externalities and some agents care about the social impact of their decisions. We show that if the majority of investors are even slightly socially responsible, voice achieves the socially optimal outcome. In contrast, exit does not unless everybody is significantly socially responsible. If the majority of investors are purely selfish, exit is a more effective strategy, but neither strategy generally achieves the first best. We also show that exit can sometimes reduce social welfare.

5.China’s Model of Managing the Financial System（RES2022）

China’s economic model involves regular and intensive government interventions in financial markets, while Western policymakers often refrain from substantial interventions outside crisis periods. We develop a theoretical framework to rationalize the approaches of both China and the West to managing the financial system as being optimal given the differences in their respective economies. In this framework, a government leans against trading of noise traders but at the expense of introducing policy noise to the market. Our welfare analysis shows that under certain underlying economic conditions, the optimal government policy induces a government-centric equilibrium, in which government intervention is so intensive that all investors choose to acquire private information about policy noise rather than fundamentals. This policy regime characterizes China’s approach with financial stability prioritized over other policy objectives.

6.Investigating the real effect of China’s patent surge: New evidence from firm-level patent quality data（JEBO2022）

This paper examines whether there was a real improvement in patent quality or productivity with the patent surge in China. Based on the novel database we compiled, we demonstrate that accumulated patent stock measured using quality metrics was positively associated with the productivity of large and medium-size enterprises (LMEs). We also find that R&D investments by LMEs led to increases in patent quality. However, the estimated R&D-patenting elasticities in China are found to be lower than those estimated in developed countries. We offer some explanations and discuss their implications for policy considerations.