Knowledge that Transforms

One in five Zambian children lives with an HIV/AIDS-infected adult. We estimate the effect that the availability of adult antiretroviral therapy (ART) has on the health of such children. Using a triple difference specification, we find that adult access to ART resulted in increased weight-for-age and decreased incidence of stunting among children younger than 60 months who resided with an infected father or other infected adult in an intact household. Because the increased availability of adult ART in sub-Saharan Africa has multigenerational effects, cost-effectiveness estimates restricted to direct recipients understate the economic benefit of the treatment.

We conducted a national survey of department Chairs to investigate whether departments of economics changed course requirements for bachelors degrees since the Siegfried and Bidani (1992) paper using 1980 data. There have been few changes to course requirements. Most notable are a large increase in the number of departments requiring econometrics and a drop in departments requiring courses such as money, banking and economic history--courses once required in many business schools.

We study risk attitudes, ambiguity attitudes, and time preferences of 661 children and adolescents, aged ten to eighteen years, in an incentivized experiment and relate experimental choices to field behavior. Experimental measures of impatience are found to be significant predictors of health-related field behavior, saving decisions, and conduct at school. In particular, more impatient children and adolescents are more likely to spend money on alcohol and cigarettes, have a higher body mass index, are less likely to save money, and show worse conduct at school. Experimental measures for risk and ambiguity attitudes are only weak predictors of field behavior.

Using data from a field experiment in Kenya, we document that providing individuals with simple informal savings technologies can substantially increase investment in preventative health and reduce vulnerability to health shocks. Simply providing a safe place to keep money was sufficient to increase health savings by 66 percent. Adding an earmarking feature was only helpful when funds were put toward emergencies, or for individuals that are frequently taxed by friends and relatives. Group-based savings and credit schemes had very large effects.

We offer a theory of polarization as an optimal response to ambiguity. Suppose individual A's beliefs first-order stochastically dominate individual B's. They observe a common signal. They exhibit polarization if A's posterior dominates her prior and B's prior dominates her posterior. Given agreement on conditional signal likelihoods, we show that polarization is impossible under Bayesian updating or after observing extreme signals. However, we also show that polarization can arise after intermediate signals as ambiguity averse individuals implement their optimal prediction strategies. We explore when this polarization will occur and the logic underlying it.

We study the mobile phone-based money transfer system in Kenya. Based on aggregate data, we estimate that the velocity with which units of e-money are transferred among users is approximately four times per month, and that the average number of transfers undergone by a unit of e-money between its creation and destruction is approximately one. Most M-Pesa transactions are made by frequent users. Examination of data on withdrawals shows a high frequency of small withdrawals and no response to “notches” in the price schedule, indicating that many users seem to have high implicit discount rates.

This article introduces a new approach to modeling the expanding universe of decision makers in the wake of growing awareness, and invokes the axiomatic approach to model the evolution of decision makers' beliefs as awareness grows. The expanding universe is accompanied by extension of the set of acts, the preference relations over which are linked by a new axiom, invariant risk preferences, asserting that the ranking of lotteries is independent of the set of acts under consideration. The main results are representation theorems and rules for updating beliefs over expanding state spaces and events that have the flavor of “reverse Bayesianism.”

Authority and power permeate political, social, and economic life, but empirical knowledge about the motivational origins and consequences of authority is limited. We study the motivation and incentive effects of authority experimentally in an authority-delegation game. Individuals often retain authority even when its delegation is in their material interest—suggesting that authority has nonpecuniary consequences for utility. Authority also leads to overprovision of effort by the controlling parties, while a large percentage of subordinates underprovide effort despite pecuniary incentives to the contrary. Authority thus has important motivational consequences that exacerbate the inefficiencies arising from suboptimal delegation choices.

This paper examines the impact of crime and insecurity on support for and satisfaction with democracy and trust in institutions. We use survey data from the Latin American Public Opinion Project (LAPOP) for Colombia during the 2004-2010 period. We find that perceptions of insecurity, crime victimization, being asked for a bribe and being affected by the armed conflict have a negative significant effect on satisfaction with democracy and trust in public institutions. Our findings show an important indirect channel through which crime can hinder development because distrust in institutions is associated with lower levels of social capital.

This paper investigates the effect of idiosyncratic (firm-level) policy distortions on aggregate outcomes. Exploiting harmonized firm-level data for a number of countries, we show that there is substantial and systematic cross-country variation in the within-industry covariance between size and productivity. We develop a model in which heterogeneous firms face adjustment frictions (overhead labor and quasi-fixed capital) and distortions. The model can be readily calibrated so that variations in the distribution of distortions allow matching the observed cross-country moments. We show that the differences in the distortions that account for the size-productivity covariance imply substantial differences in aggregate performance.