When does a common group identity improve efficiency in coordination games? To answer this question, we propose a group-contingent social preference model and derive conditions under which social identity changes equilibrium selection. We test our predictions in the minimum-effort game in the laboratory under parameter configurations which lead to an inefficient low-effort equilibrium for subjects with no group identity. For those with a salient group identity, consistent with our theory, we find that learning leads to ingroup coordination to the efficient high-effort equilibrium. Additionally, our theoretical framework reconciles findings from a number of coordination game experiments.

This paper investigates a sequential social learning problem in which individuals face ambiguity about others’ signal structures and have max-min expected utility preferences, thereby exhibiting ambiguity aversion. Unlike previous findings, which suggest that learning outcomes depend on the specifics of the learning environment, this study establishes information cascades as a robust outcome under ambiguity. With sufficient ambiguity, cascades arise almost surely, regardless of the statistical properties of signal structures. Moreover, standard results predicting the absence of cascades can easily break down: Even minimal ambiguity can trigger cascades when signals are bounded and lead to incorrect herding when signals are unbounded.

Languages differ widely in the ways they encode time. I test the hypothesis that the languages that grammatically associate the future and the present, foster future-oriented behavior. This prediction arises naturally when well-documented effects of language structure are merged with models of intertemporal choice. Empirically, I find that speakers of such languages: save more, retire with more wealth, smoke less, practice safer sex, and are less obese. This holds both across countries and within countries when comparing demographically similar native households. The evidence does not support the most obvious forms of common causation. I discuss implications for theories of intertemporal choice.

This paper studies the productivity of nurse practitioners (NPs) and physicians, two professions performing overlapping tasks but with starkly different backgrounds, training, and pay. Using quasi-experimental variation in patient assignment to NPs versus physicians in Veterans Health Administration emergency departments, we find that, on average, NPs use more resources and exhibit a higher 30-day preventable hospitalization rate than physicians. However, the NP-physician performance difference varies by case complexity and severity. Importantly, even larger productivity variation exists within each profession, leading to substantial overlap between the productivity distributions of the two professions; NPs outperform physicians in 38 percent of random pairs.

In existing theory, wealth is no more valuable than its implied consumption rewards. In reality investors acquire wealth not just for its implied consumption, but for the resulting social status. Max M. Weber refers to this desire for wealth as the spirit of capitalism. We examine, both analytically and empirically, implications of Weber's hypothesis for consumption, savings, and stock prices. When investors care about relative social status, propensity to consume and risk-taking behavior will depend on social standards, and stock prices will be volatile. The spirit of capitalism seems to be a driving force behind stock-market volatility and economic growth.

The Impact of Unexpected Maternal Death on Education: First Evidence from Three National Administrative Data Links by Stacey H. Chen, Yen-Chien Chen and Jin-Tan Liu. Published in volume 99, issue 2, pages 149-53 of American Economic Review, May 2009

This paper studies whether team members’ past collaboration creates team-specific human capital and influences current team performance. Using administrative Medicare claims for two heart procedures, I find that shared work experience between the doctor who performs the procedure (“proceduralist”) and the doctors who provide care to the patient during the hospital stay for the procedure (“physicians”) reduces patient mortality rates. A one standard deviation increase in proceduralist-physician shared work experience leads to a 10–14 percent reduction in patient 30-day mortality. Patient medical resource use also declines with shared work experience, even as survival improves.

Zhao (2008) presents an interesting “all-or-nothing monitoring” result for a multitask moral hazard agency problem with partial effort observation. We argue that the optimal contract based on the non-verifiable observation of the agent's effort in Zhao (2008) can be regarded as a limitation on the incentive schemes available to the principal. I then propose some arguably more appropriate approaches for analyzing such agency problems. (D82, D86, M54)

Despite much work, economists have not been able to quantitatively account for the differences in the Japanese and U.S. saving rates after World War II. In this paper, we show that the use of actual Japanese total factor productivity growth rates in a standard growth model generates saving rates that are reasonably similar to the Japanese data between 1956 and 2000.