Latest Research Publications

Empirical researchers are increasingly faced with rich data sets containing many controls or instrumental variables, making it essential to choose an appropriate approach to variable selection. In this paper, we provide results for valid inference after post- or orthogonal L2-boosting is used for variable selection. We consider treatment effects after selecting among many control variables and instrumental variable models with potentially many instruments. To achieve this, we establish new results for the rate of convergence of iterated post-L2-boosting and orthogonal L2-boosting in a high-dimensional setting similar to Lasso, i.e., under approximate sparsity without assuming the beta-min condition. These results are extended to the 2SLS framework and valid inference is provided for treatment effect analysis. We give extensive simulation results for the proposed methods and compare them with Lasso. In an empirical application, we construct efficient IVs with our proposed methods to estimate the effect of pre-merger overlap of bank branch networks in the US on the post-merger stock returns of the acquirer bank.

Risk premia increase with government debt. Debt-to-GDP ratios positively predict stock returns at short and long horizons in the U.S. and other advanced economies. Higher debt is also associated with higher bond premia and lower risk-free rates. Major government debt theories (liquidity, safety, crowding out) either do not address or are inconsistent with these findings. New evidence suggests that the increased risk premia provide compensation for larger fiscal risk; during periods of elevated debt, fiscal policy becomes more uncertain and less effective and can lead to debt crises. I quantify these mechanisms in an equilibrium model.

Shared coupons, a new form of coupon, differ from coupons distributed directly from businesses (i.e., direct coupons) in that shared coupons combine two influential components: economic savings (e.g., $5 off) and social sharing (e.g., from friends). Using two lab experiments and two large-scale field experiments on social media, the authors find that regular shared coupons underperform direct coupons in terms of coupon redemption because of the norm conflict between economic incentives and communal relationships (i.e., friendships), whereas shared coupons with experience cocreation, in which coupon givers and coupon receivers must invest joint efforts to create a shared experience before redeeming the coupons, outperform direct coupons. Experience cocreation can advance social goals (e.g., building friendships), reduce the norm conflict, and thereby make customers more likely to share and to redeem coupons. The authors further investigate the effects of two strategies for driving the redemption of shared coupons with experience cocreation: changing the coupon's face value (low vs. high) and using ex post communication (social messages vs. economic messages). They find that social messages can make low-value coupons as effective as high-value coupons, thereby enabling the firm to “do more with less.”

The coronavirus/SARS-CoV-2 (COVID-19) outbreak has caused severe supply chain disruptions in practically all industries worldwide. Online e-commerce platforms, which interact directly with various industries and service numerous consumers, have become remarkable interfaces to observe the impacts of the pandemic on supply chains. Using quantitative operational data obtained from JD.com https://www.jd.com., this study analyzes the impact of the pandemic on supply chain resilience, summarizes the challenging scenarios that retailing supply chains experienced in China, and presents the practical response of JD.com throughout the pandemic. To summarize, the pandemic caused exceptional demand and severe logistical disruptions in China, and JD.com has handled well its supply chain management in response based on its integrated supply chain structure and comprehensive intelligent platforms. In particular, the existing intelligent platforms and the delivery procedures were modified slightly but promptly to deal with specific disruptions. Moreover, the entire market scenario in China was effectively controlled through the joint efforts of multiple firms, the government, and the entire Chinese society. Our study provides an example of using practical operational indicators to analyze supply chain resilience, and suggests firms pay attention to operational flexibility and collaboration beyond supply chains to deal with a large-scale supply chain disruption, such as the COVID-19 outbreak.

This paper examines how female directors (FDs) affect firm value in the absence of mandatory gender quotas. Using a newly collected data set on director deaths around the globe, we find that stock prices decrease approximately 2% more when an FD passes away, compared with a male director. What explains this negative capital market reaction? We find evidence that finding successors for deceased FDs is challenging for firms: Succession delays are longer, and although firms try to replace FDs with women, two-thirds of their successors are male. Furthermore, their successors tend to be younger, less experienced, and more often externally hired. Stock prices decline less if more potential female successors exist in a country, the firm is larger, or FDs other than the deceased woman were on the board. Because observable characteristics such as age, tenure, education, and network centrality cannot explain the negative stock market reaction, unobserved differences across genders that lead to a lower fit of male successors to the existing board are the most likely explanation for the firm value loss after the death of an FD.

Drawing from research on the transparency-privacy dilemma in management, we theorize that firm-level pay transparency elicits a multistep process involving managers and employees that shifts the dispersion in remuneration from more to less observable forms, thus making pay transparency a “moving target.” We posit a serial indirect effect of pay transparency on firm-level rates of i-deal grants (a less observable form of remuneration) via variable pay compression and heightened rates of employee i-deal requests, with this indirect effect amplified in firms characterized by collectivist shared values. First examining the role of managerial agency and collectivist shared values in the pay transparency–compression relationship in a simulation-based experiment, we test the overall model in a multisource field study using a sample of 111 medical device distribution firms. Our findings demonstrate that: (a) firm-level pay transparency is predictive of greater pay compression, (b) firm-level rates of i-deal grants are largely explained by this pay compression via its effects on employee i-deal requests, and (c) this sequential effect is amplified in firms with more collectivist shared values. Accordingly, we explicate how transparency triggers unintentional hiding, and suggest that accompanying more transparent pay may be an increased reliance upon rewards that, by their very nature, are less transparent.

Following the Fukushima nuclear accident, Japan gradually shut down all its nuclear power plants, causing a countrywide power shortage. In response the government launched large-scale energy-saving campaigns to reduce electricity consumption. Exploiting the electricity-saving targets across regions and over time, we show that the campaigns significantly increased mortality, particularly during extremely hot days. The impact is primarily driven by people using less air conditioning, as encouraged by the government. Nonpecuniary incentives can explain most of the reduction in electricity consumption. Our findings suggest there exists a trade-off between climate change mitigation and climate change adaptation.

We develop a theory of blockchain governance. In our model, the proof-of-work system, the most common set of rules for validating transactions in blockchains, creates an industrial ecosystem with specialized suppliers of goods and services. We analyze the interactions between blockchain governance and the market structure of the industries in the blockchain ecosystem. We show that the proof-of-work system may lead to a situation in which some large firms in the blockchain industrial ecosystem—blockchain conglomerates—capture the governance of the blockchain.

Stock returns during the week are negatively associated with the reported incidence of domestic violence during the weekend. This relationship is primarily driven by negative returns. The incidence of domestic violence increases with the magnitude of losses, and the effect increases with local stock market participation. Our findings suggest that negative wealth shocks caused by stock market crashes can affect stress levels within intimate relationships, escalate arguments, and trigger domestic violence. Stock market losses may reduce household utility beyond the shock to financial wealth, supporting gain-loss models where disutility from losses outweighs the utility from gains of a similar magnitude.