Research

We show that unexpected changes in the trajectory of COVID-19 infections predict US stock returns, in real time. Parameter estimates indicate that an unanticipated doubling (halving) of projected infections forecasts next-day decreases (increases) in aggregate US market value of 4 to 11 percent, indicating that equity markets may begin to rebound even as infections continue to rise, if the trajectory of the disease becomes less severe than initially anticipated. Using the same variation in unanticipated projected cases, we find that COVID-19-related losses in market value at the firm level rise with capital intensity and leverage, and are deeper in industries more conducive to disease transmission. These relationships provide important insight into current record job losses. Measuring US states' drops in market value as the employment weighted average declines of the industries they produce, we find that states with milder drops in market value exhibit larger initial jobless claims per worker. This initially counter-intuitive result suggests that investors value the relative ease with which labor versus capital costs can be shed as revenues decline.

We used a randomized experimental vignette study to assess the effects of sunset clauses and conditional sunset clauses on support for proposed legislation, perceived legitimacy of legislation, and perceived good faith of legislators. In general, we hypothesized that including both types of sunset clause would increase support for legislation, increase perceived legitimacy, and increase perceived good faith. We also varied the political valence of legislation to identify whether the impact of sunset clauses varies depending on whether the legislation aligns with political viewpoint. We hypothesized that sunset clauses may increase support for laws that run contrary to political views. Our sample included 1639 adults from throughout the U.S. Participants tended to be more supportive of neutral laws compared to laws with liberal or conservative valence. Across all participants, we found that adding a sunset clause or a conditional sunset clause did not significantly affect overall support for the law, holding political valence and topic area constant. Our findings, however, showed consistently that the sunsets tended to increase support for conservative laws more than they increased support for laws that were liberal or neutral in valence. Pairwise comparisons showed that when the policy was conservative, a sunset clause and a conditional sunset clause each significantly increased support compared to no sunset. Among Liberal participants, adding either type of sunset significantly increased support for a conservative policy (p<0.05). Among Conservative participants, we found that sunsets did not affect support for liberal policies, but they marginally increased support for laws that were already conservative. Overall, sunset clauses tended to induce a broader range of compromise beliefs and significantly more compromise support for conservative legislation, compared to liberal legislation.

When physicians whom patients do not choose and cannot avoid can bill out of network for care delivered within in-network hospitals, it exposes patients to financial risk and undercuts the functioning of health care markets. Using data for 2015 from a large commercial insurer, we found that at in-network hospitals, 11.8 percent of anesthesiology care, 12.3 percent of care involving a pathologist,
5.6 percent of claims for radiologists, and 11.3 percent of cases involving an assistant surgeon were billed out of network. The ability to bill out of network allows these specialists to negotiate artificially high in-network rates. Out-of-network billing is more prevalent at hospitals in concentrated hospital and insurance markets and at for-profit hospitals. Our estimates show that if these specialists were not able to bill out of network, it would lower physician payments for privately insured patients by 13.4 percent and reduce health care spending for people with employer-sponsored insurance by 3.4 percent (approximately $40 billion annually).

Social movements are associated with large societal changes, but evidence of their causal effects is limited. We study the effect of the MeToo movement on reporting sex crimes to the police. We construct a new dataset of crimes reported in 31 OECD countries and employ a triple-difference strategy between crime types, across countries, and over time. The movement increased the reporting of sex crimes by 10%. Using rich US data, we find that in contrast to a common criticism of the movement, the effect is similar across socioeconomic groups, and that the movement also increased arrests for sexual assault. The increased reporting reflects a higher propensity to report sex crimes and not an increase in crime incidence. The mechanism most consistent with our findings is that victims perceive sexual misconduct to be a more serious problem following the movement. Our results demonstrate that social movements can rapidly and persistently affect high-stakes decisions. 

We study the effects of defaults on charitable giving in a large-scale field experiment on an online fundraising platform. We exogenously vary default options along two choice dimensions: the charitable donation decision and the “co-donation” decision regarding how much to contribute to supporting the platform. We document a strong effect of defaults on individual behavior but nevertheless find that aggregate donation levels are unaffected by defaults. In contrast, co-donations increase in the default amount. We complement our experimental results with a structural model that investigates whether personalizing defaults based on individuals' donation histories can increase donation revenues.

Job differentiation gives employers market power, allowing them to pay workers less than their marginal productivity. We estimate a differentiated jobs model using application data from Careerbuilder.com. We find direct evidence of substantial job differentiation. Without the use of instruments for wages, job applications appear very inelastic with respect to wages. Plausible instruments produce elastic firm level application supply curves. Under some assumptions, the implied market level labor supply elasticity is 0.5, while the firm level labor elasticity is 4.8. This suggests that workers may produce 21% more than their wage level, consistent with significant monopsony power.

Many countries face growing concerns that population aging may make voting and policy-making myopic. This concern begs for electoral reform to better reflect voices of the youth, such as weighting votes by voters' life expectancy. This paper predicts the effect of the counterfactual electoral reform on the 2016 U.S. presidential election. Using the American National Election Studies (ANES) data, I find that Hillary Clinton would have won the election if votes were weighted by life expectancy. I also discuss limitations due to data issues.

We use insurance claims data covering 28% of individuals with employer-sponsored health insurance in the United States to study the variation in health spending on the privately insured, examine the structure of insurer-hospital contracts, and analyze the variation in hospital prices across the nation. Health spending per privately insured beneficiary differs by a factor of three across geographic areas and has a very low correlation with Medicare spending. For the privately insured, half of the spending variation is driven by price variation across regions, and half is driven by quantity variation. Prices vary substantially across regions, across hospitals within regions, and even within hospitals. For example, even for a nearly homogeneous service such as lower-limb magnetic resonance imaging, about a fifth of the total case-level price variation occurs within a hospital in the cross section. Hospital market structure is strongly associated with price levels and contract structure. Prices at monopoly hospitals are 12% higher than those in markets with four or more rivals. Monopoly hospitals also have contracts that load more risk on insurers (e.g., they have more cases with prices set as a share of their charges). In concentrated insurer markets the opposite occurs—hospitals have lower prices and bear more financial risk. Examining the 366 mergers and acquisitions that occurred between 2007 and 2011, we find that prices increased by over 6% when the merging hospitals were geographically close (e.g., 5 miles or less apart), but not when the hospitals were geographically distant (e.g., over 25 miles apart). JEL Codes: I11, L10, L11.

Evidence suggests that growth in providers’ prices drives growth in health care spending on the privately insured. However, existing work has not systematically differentiated between the growth rate of hospital prices and that of physician prices. We analyzed growth in both types of prices for inpatient and hospital-based outpatient services using actual negotiated prices paid by insurers.

We found that in the period 2007–14 hospital prices grew substantially faster than physician prices. For inpatient care, hospital prices grew 42 percent, while physician prices grew 18 percent. Similarly, for hospital-based outpatient care, hospital prices grew 25 percent, while physician prices grew 6 percent. A majority of the growth in payments for inpatient and hospital-based outpatient care was driven by growth in hospital prices, not physician prices.

Our work suggests that efforts to reduce health care spending should be primarily focused on addressing growth in hospital rather than physician prices. Policymakers should consider a range of options to address hospital price growth, including antitrust enforcement, administered pricing, the use of reference pricing, and incentivizing referring physicians to make more cost-efficient referrals.

We examined the growth in health spending on people with employer-sponsored private insurance in the period 2007–14. Our analysis relied on information from the Health Care Cost Institute data set, which includes insurance claims from Aetna, Humana, and UnitedHealthcare. In the study period private health spending per enrollee grew 16.9 percent, while growth in Medicare spending per fee-for-service beneficiary decreased 1.2 percent. There was substantial variation in private spending growth rates across hospital referral regions (HRRs): Spending in HRRs in the tenth percentile of private spending growth grew at 0.22 percent per year, while HRRs in the ninetieth percentile experienced 3.45 percent growth per year. The correlation between the growth in HRR-level private health spending and growth in fee-for-service Medicare spending in the study period was only 0.211. The low correlation across HRRs suggests that different factors may be driving the growth in spending on the two populations.

This paper examines the impact of a government programme which facilitated the entry of for-profit surgical centres to compete against incumbent National Health Service hospitals in England. We examine the impact of competition from these surgical centres on the efficiency – measured by pre-surgery length of stay for hip and knee replacement patients – and case mix of incumbent public hospitals. We exploit the fact that the government chose the broad locations where these surgical centres (Independent Sector Treatment Centres or ISTCs) would be built based on local patient waiting times – not length of stay or clinical quality – to construct treatment and control groups that are comparable with respect to key outcome variables of interest. Using a difference-in-difference estimation strategy, we find that the government-facilitated entry of surgical centres led to shorter pre surgery length of stay at nearby public hospitals. However, these new entrants took on healthier patients and left incumbent hospitals treating patients who were sicker. This paper highlights a potential trade-off that policymakers face when they promote competition from private, for-profit firms in markets for the provision of public services.

A growing number of school districts use centralized assignment mechanisms to allocate school seats in a manner that reflects student preferences and school priorities. Many of these assignment schemes use lotteries to ration seats when schools are oversubscribed. The resulting random assignment opens the door to credible quasi-experimental research designs for the evaluation of school effectiveness. Yet the question of how best to separate the lottery-generated randomization integral to such designs from non-random preferences and priorities remains open. This paper develops easily-implemented empirical strategies that fully exploit the random assignment embedded in a wide class of mechanisms, while also revealing why seats are randomized at one school but not another. We use these methods to evaluate charter schools in Denver, one of a growing number of districts that combine charter and traditional public schools in a unified assignment system. The resulting estimates show large achievement gains from charter school attendance. Our approach generates efficiency gains over ad hoc methods, such as those that focus on schools ranked first, while also identifying a more representative average causal effect. We also show how to use centralized assignment mechanisms to identify causal effects in models with multiple school sectors.

We quantify the distortionary effects of nexus tax laws on Amazon’s distribution network investments between 1999 and 2018. We highlight the role of two features of the expansion of Amazon’s network: densification of the network of distribution facilities and vertical integration into package sortation. Densification results in a reduction in the cost of shipping orders, but comes at the expense of higher facility operating costs in more expensive areas and lower scale economies of processing shipments. Nexus laws furthermore generate additional sales tax liabilities as the network grows. Combining data on household spending across online and offline retailers with detailed data on Amazon’s distribution network, we quantify these trade-offs through a static model of demand and a dynamic model of investment. Our results suggest that Amazon’s expansion led to significant shipping cost savings and facilitated the realization of aggregate economies of scale. We find that abolishing nexus tax laws in favor of a non-discriminatory tax policy would induce the company to decentralize its network, lowering its shipping costs. Non-discriminatory taxation would also entail lower revenue, however, as tax-inclusive prices would rise, resulting in a fall in profit overall. This drop and the decline in consumer welfare from higher taxes together fall short of the increases in tax revenue and rival profit, suggesting that the abolishment of nexus laws would lead to an increase in total welfare.

The goal of antitrust policy is to protect and promote a vigorous competitive process. Effective rivalry spurs firms to introduce new and innovative products, as they seek to capture profitable sales from their competitors and to protect their existing sales from future challengers. In this fundamental way, competition promotes innovation. We apply this basic insight to the antitrust treatment of horizontal mergers and of exclusionary conduct by dominant firms. A merger between rivals internalizes business-stealing effects arising from their parallel innovation efforts and thus tends to depress innovation incentives. Merger-specific synergies, such as the internalization of involuntary spillovers or an increase in the productivity of R&D, may offset the adverse effect of a merger on innovation. We describe the possible effects of a merger on innovation by developing a taxonomy of cases, with reference to recent US and EU examples. A dominant firm may engage in exclusionary conduct to eliminate the threat from disruptive firms. This suppresses innovation by foreclosing disruptive rivals and by reducing the pressure to innovative on the incumbent. We apply this broad principle to possible exclusionary strategies by dominant firms.