Knowledge that Transforms

We exploit variation in mortgage modifications to disentangle the impact of reducing long-term obligations with no change in short-term payments (“wealth”), and reducing short-term payments with no change in long-term obligations (“liquidity”). Using regression discontinuity and difference-in-differences research designs with administrative data measuring default and consumption, we find that principal reductions that increase wealth without affecting liquidity have no effect, while maturity extensions that increase only liquidity have large effects. This suggests that liquidity drives default and consumption decisions for borrowers in our sample and that distressed debt restructurings can be redesigned with substantial gains to borrowers, lenders, and taxpayers. (JEL E21, G21, G51, R38)

We study the rationality of individual and consensus forecasts of macroeconomic and financial variables using the methodology of Coibion and Gorodnichenko (2015), who examine predictability of forecast errors from forecast revisions. We find that individual forecasters typically overreact to news, while consensus forecasts under-react relative to full-information rational expectations. We reconcile these findings within a diagnostic expectations version of a dispersed information learning model. Structural estimation indicates that departures from Bayesian updating in the form of diagnostic overreaction capture important variation in forecast biases across different series, yielding a belief distortion parameter similar to estimates obtained in other settings. (JEL C53, D83, D84, E13, E17, E27, E47)

People reason about uncertainty with deliberately incomplete models. How do people hampered by different, incomplete views of the world learn from each other? We introduce a model of “ model-based inference.” Model-based reasoners partition an otherwise hopelessly complex state space into a manageable model. Unless the differences in agents’ models are trivial, interactions will often not lead agents to have common beliefs or beliefs near the correct-model belief. If the agents’ models have enough in common, then interacting will lead agents to similar beliefs, even if their models also exhibit some bizarre idiosyncrasies and their information is widely dispersed. (JEL D82, D83)

This paper studies how welfare outcomes in centralized school choice depend on the assignment mechanism when participants are not fully informed. Using a survey of school choice participants in a strategic setting, we show that beliefs about admissions chances differ from rational expectations values and predict choice behavior. To quantify the welfare costs of belief errors, we estimate a model of school choice that incorporates subjective beliefs. We evaluate the equilibrium effects of switching to a strategy-proof deferred acceptance algorithm, and of improving households’ belief accuracy. We find that a switch to truthful reporting in the DA mechanism offers welfare improvements over the baseline given the belief errors we observe in the data, but that an analyst who assumed families had accurate beliefs would have reached the opposite conclusion. (JEL D83, H75, I21, I28)

We study the complexity of rules by paying experimental subjects to implement a series of algorithms and then eliciting their willingness-to-pay to avoid implementing them again in the future. The design allows us to examine hypotheses from the theoretical “automata” literature about the characteristics of rules that generate complexity costs. We find substantial aversion to complexity and a number of regularities in the characteristics of rules that make them complex and costly for subjects. Experience with a rule, the way a rule is represented, and the context in which a rule is implemented (mentally versus physically) also influence complexity. (JEL C73, D11, D12, D83, D91)

Macroeconomic news announcements are elaborate and multidimensional. We consider a framework in which jumps in asset prices around announcements reflect both the response to observed surprises in headline numbers and to latent factors, reflecting other news in the release. Non-headline news, for which there are no expectations surveys, is unobservable to the econometrician but nonetheless elicits a market response. We estimate the model by the Kalman filter, which efficiently combines OLS and heteroskedasticity-based event study estimators in one step. With the inclusion of a single latent surprise factor, essentially all yield curve variance in event windows are explained by news. (JEL C51, E43, E52, G12, G14)

Fang and Gong (2017) develop a procedure to detect potential over-billing of Medicare by physicians. In their empirical analysis, they use aggregated claims data that can overstate the number of services performed due to features of Medicare billing. In this comment, I show how auditors can use detailed claims-level data to better target improper overbilling. (JEL H51, I13, I18, J22, J44)

The experimental method not only helps identify causal relationships, but also provides economists with a rich sense of context, focuses research on specific practical questions, stimulates collaboration with practitioners and specialists from other fields, and allows for rapid iteration. In this lecture, I present a series of examples illustrating how together these features make the experimental approach a powerful tool for advancing scientific understanding, informing policy, and promoting innovation. I then discuss how institutions can be designed to accelerate innovation and direct it toward the world’s most pressing needs. (JEL B31, C90, I10, O15, O30, O43)

Social norms, usually persistent, can change quickly when new public information arrives, such as a surprising election outcome. People may become more inclined to express views or take actions previously perceived as stigmatized and may judge others less negatively for doing so. We examine this possibility using two experiments. We first show via revealed preference experiments that Donald Trump’s rise in popularity and eventual victory increased individuals’ willingness to publicly express xenophobic views. We then show that individuals are sanctioned less negatively if they publicly expressed a xenophobic view in an environment where that view is more popular. (JEL D72, D85, Z13)

We study multi-district legislative elections between two office-seeking parties when one party has an initial valence advantage that may shift and even reverse during the campaign; and, each party cares not only about winning a majority, but also about its share of seats. When the initial imbalance favoring one party is small, each party targets the median voter. For moderate imbalances, the advantaged party maintains the centre-ground, but the disadvantaged party retreats to target its core supporters; and for large imbalances, the advantaged party advances toward its opponent, raiding its moderate supporters in pursuit of an outsized majority. (JEL D72)