We develop a model of political cycles driven by time-varying risk aversion. Agents choose to work in the public or private sector and to vote Democratic or Republican. In equilibrium, when risk aversion is high, agents elect Democrats—the party promising more redistribution. The model predicts higher average stock market returns under Democratic presidencies, explaining the well-known “presidential puzzle.” The model can also explain why economic growth has been faster under Democratic presidencies. In the data, Democratic voters are more risk averse, and risk aversion declines during Democratic presidencies. Public workers vote Democratic, while entrepreneurs vote Republican, as the model predicts.
参考文献：Pástor, Ľ., Veronesi, P., 2020. Political Cycles and Stock Returns. Journal of Political Economy 128, 4011–4045.
二、医生如何应对激励？付钱给医生以降低医疗成本的意外后果
How Do Doctors Respond to Incentives? Unintended Consequences of Paying Doctors to Reduce Costs
Billions of dollars have been spent on pilot programs searching for ways to reduce health care costs. I study one such program, in which hospitals pay doctors bonuses for reducing the total hospital costs of admitted Medicare patients. Doctors respond to the bonuses by becoming more likely to admit patients whose treatment can generate high bonuses and sorting healthier patients into participating hospitals. Conditional on patient health, however, doctors do not reduce costs or change procedure use. These results highlight the ability of doctors to game incentive schemes and the risks of basing nationwide health care reforms on pilot programs.
参考文献：Alexander, D., 2020. How Do Doctors Respond to Incentives? Unintended Consequences of Paying Doctors to Reduce Costs. Journal of Political Economy 128, 4046–4096.
Firm volatilities comove strongly over time, and their common factor is the dispersion of the economy-wide firm size distribution. In the cross section, smaller firms and firms with a more concentrated customer base display higher volatility. Network effects are essential to explaining the joint evolution of the empirical firm size and firm volatility distributions. We propose and estimate a simple network model of firm volatility in which shocks to customers influence their suppliers. Larger suppliers have more customers, and customer-supplier links depend on customers’ size. The model produces distributions of firm volatility, size, and customer concentration consistent with the data.
参考文献：Herskovic, B., Kelly, B., Lustig, H., Van Nieuwerburgh, S., 2020. Firm Volatility in Granular Networks. Journal of Political Economy 128, 4097–4162.
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四、版权和创造力：拿破仑时代意大利歌剧的证据
Copyrights and Creativity: Evidence from Italian Opera in the Napoleonic Age
This paper exploits variation in the adoption of copyrights within Italy—due to the timing of Napoléon’s military victories—to investigate the causal effects of copyrights on creativity. Baseline regressions compare changes in opera production across Italian states with and without copyrights. This analysis yields three main results. First, the adoption of copyrights led to a significant increase in the number of newly created operas. Second, copyrights raised the quality of new operas, measured both by their immediate success and by their longevity. Third, there were no benefits from copyright extensions beyond the life of the original creator.
参考文献：Michela Giorcelli & Petra Moser, 2020. "Copyrights and Creativity: Evidence from Italian Opera in the Napoleonic Age," Journal of Political Economy, University of Chicago Press, vol. 128(11), pages 4163-4210.
Using employer-employee matched and firm production quantity and input data for Portuguese firms, we study the endogenous response of productivity to firm reorganizations as measured by changes in the number of management layers. We show that, as a result of an exogenous demand or productivity shock that makes the firm reorganize and add a management layer, quantity-based productivity increases by about 6%, while revenue-based productivity drops by around 3%. Such a reorganization makes the firm more productive but also increases the quantity produced to an extent that lowers the price charged by the firm and, as a result, its revenue-based productivity as well.
参考文献：Lorenzo Caliendo & Giordano Mion & Luca David Opromolla & Esteban Rossi-Hansberg, 2020. "Productivity and Organization in Portuguese Firms," Journal of Political Economy, University of Chicago Press, vol. 128(11), pages 4211-4257.
六、均衡劳动力市场搜索与健康保险改革
Equilibrium Labor Market Search and Health Insurance Reform
We present and empirically implement an equilibrium labor market search model where risk-averse workers facing medical expenditure shocks are matched with firms making health insurance coverage decisions. We use our estimated model to evaluate the equilibrium impact of many health care reform proposals, including the 2010 Affordable Care Act (ACA). We use the estimates of the early impact of the ACA as a model validation. We find that income-based subsidies for health insurance premiums are crucial for the sustainability of the ACA, while the ACA can still substantially reduce the uninsured rate without the individual or the employer mandate.
参考文献：Aizawa, N., Fang, H., 2020. Equilibrium Labor Market Search and Health Insurance Reform. Journal of Political Economy 128, 4258–4336.
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七、职业执照和孕产妇保健：早期助产法的证据
Occupational Licensing and Maternal Health: Evidence from Early Midwifery Laws
Exploiting variation across states and municipalities in the timing and details of midwifery laws introduced during the period 1900–1940 and using data assembled from various primary sources, we find that requiring midwives to be licensed reduced maternal mortality by 7%–8% and may have led to modest reductions in infant mortality. These estimates represent the strongest evidence to date that licensing restrictions can improve the health of consumers and are directly relevant to ongoing policy debates on the merits of licensing midwives.
