Knowledge that Transforms

South Korea publicly disclosed detailed location information of individuals who tested positive for COVID-19. We quantify the effect of public disclosure on the transmission of the virus and economic losses in Seoul. The change in commuting patterns due to public disclosure lowers the number of cases by 60,000 and the number of deaths by 2,000 in Seoul over two years. Compared to a city-wide lockdown that results in the same number of cases over two years as the disclosure scenario, the economic cost of such a lockdown is almost four times higher.

How feasible is violence early-warning prediction? Colombia and Indonesia have unusually fine-grained data. We assemble two decades of local violent events alongside hundreds of annual risk factors. We attempt to predict violence one year ahead with a range of machine learning techniques. Our models reliably identify persistent, high-violence hot spots. Violence is not simply autoregressive, as detailed histories of disaggregated violence perform best, but socioeconomic data substitute well for these histories. Even with unusually rich data, however, our models poorly predict new outbreaks or escalations of violence. These “best-case” scenarios with annual data fall short of workable early-warning systems.

In 1978, California adopted building codes designed to reduce the energy used for temperature control. Using a rich data set of hourly electricity consumption for 158,112 houses in Sacramento, we estimate that the average house built just after 1978 uses 8% to 13% less electricity for cooling than a similar house built just before 1978. Comparing the estimated savings to the policy's projected cost, our results suggest the policy passes a cost-benefit test. In settings where market failures prevent energy costs from being completely passed through to home prices, building codes can serve as a cost- effective tool for improving energy efficiency.

In light of the debate over inclusive education, this paper evaluates the impact of exposure to special needs (SN) peers. More classroom peers with SN lower performance, the probability of entering postcompulsory education, and income at ages 17 to 25. SN students and students at the lower end of the achievement distribution suffer most from higher inclusion. We analyze the effects of reallocation policies to alleviate negative externalities, and demonstrate that inclusion is preferable to segregation in terms of maximizing average test scores.

What do patents tell us about the economic effects of future technological improvements? We identify aggregate and industry-level patent-based news shocks by exploiting changes in stock market valuations of firms that obtain patent grants. Our shocks resemble diffusion news: they do not affect total factor productivity in the short run but induce a strong permanent effect after five years. We find that patent-based news shocks produce positive co-movement between consumption, output, investment, and hours. They also generate positive responses in inflation and in the federal funds rate, consistent with standard New Keynesian models.

While episodes of financial distress are followed by large and persistent drops in economic activity, structural time series analyses point to relatively mild and transitory effects of financial market disruptions. We argue that these seemingly contradictory findings are due to the asymmetric effects of financial shocks, which have been predicted theoretically but not taken into account empirically. We estimate a model designed to identify the (possibly asymmetric) effects of financial market disruptions, and we find that a favorable financial shock—an easing of financial conditions—has little effect on output, but an adverse shock has large and persistent effects. In a counterfactual exercise, we find that over two-thirds of the gap between current US GDP and its 207 precrisis trend was caused by the 2007–2008 financial shocks.

Equal access to voting is a core feature of democratic government. Using data from hundreds of thousands of smartphone users, we quantify a racial disparity in voting wait times across a nationwide sample of polling places during the 2016 U.S. presidential election. Relative to entirely white neighborhoods, residents of entirely black neighborhoods waited 29% longer to vote and were 74% more likely to spend more than thirty minutes at their polling place. This disparity holds when comparing predominantly white and black polling places within the same states and counties and survives numerous robustness and placebo tests. We shed light on the mechanism for these results and discuss how geospatial data can be an effective tool to measure and monitor these disparities going forward.

Do individuals care about their relative income? While this is a long-standing hypothesis, revealed-preference evidence remains elusive. We provide a unique test by studying residential choices: individuals often must choose between places with different income distributions, and as a result they “choose” their relative income. We conducted a field experiment with 1,080 senior medical students who participated in the National Resident Matching Program. We estimate their preferences by combining choice data, survey data on perceptions, and information-provision experiments. The evidence suggests that individuals care about their relative income and that these preferences differ across single and nonsingle individuals.

We assess the role of monetary incentives in a mission-oriented organization by randomly assigning workers to one of two bonus schemes, incentivizing either the performance of a microcredit program (bottom line) or the empowerment of clients (mission). We find that the credit bonus improved credit-related outcomes but undermined the social mission, while the social bonus did not harm the bottom line. These results are consistent with a multitasking model with production spillovers or with prosocial behavior. We show that when mission-related rewards are not feasible, organizations that care about both the mission and the bottom line prefer flat wages to incentives.

We estimate the causal impact of military conscription on long-term beliefs and personality traits. To address potential endogeneity concerns, we exploit the conscription lottery in Argentina. We combine administrative data from the conscription lottery with data from a survey we designed on beliefs and personality traits. We find that men who were conscripted are more likely to adopt a military mind-set and that the effect is long lasting. Given the many people who go through military conscription, our results are useful for understanding how personality traits and beliefs are formed for a very salient part of the world's population.