Knowledge that Transforms

In this paper we study the causal impact of police on crime, looking at what happened to crime and police before and after the terror attacks that hit central London in July 2005. The attacks resulted in a large redeployment of police officers to central London as compared to outer London. During this time, crime fell significantly in central relative to outer London. The instrumental variable approach we use uncovers an elasticity of crime with respect to police of approximately -0.3 to -0.4, so that a 10 percent increase in police activity reduces crime by around 3 to 4 percent. JEL: K42

American Economic Association Universal Academic Questionnaire Summary Statistics by Charles E. Scott and John J. Siegfried. Published in volume 101, issue 3, pages 664-67 of American Economic Review, May 2011

Although experimental studies have documented systematic decision errors, many leading scholars believe that experience, competition, and large stakes will reliably extinguish biases. We test for the presence of a fundamental bias, loss aversion, in a high-stakes context: professional golfers' performance on the PGA Tour. Golf provides a natural setting to test for loss aversion because golfers are rewarded for the total number of strokes they take during a tournament, yet each individual hole has a salient reference point, par. We analyze over 2.5 million putts using precise laser measurements and find evidence that even the best golfers—including Tiger Woods—show evidence of loss aversion.

We consider estimation of population averages when data are missing at random. If some cells contain few observations, there can be substantial gains from imposing parametric restrictions on the cell means, but there is also a danger of misspecification. We develop a simple empirical Bayes estimator, which combines parametric and unadjusted estimates of cell means in a data-driven way. We also consider ways to use knowledge of the form of the propensity score to increase robustness. We develop an empirical Bayes extension of a double robust estimator. In a small simulation study, the empirical Bayes estimators perform well. They are similar to fully nonparametric methods and robust to misspecification when cells are moderate to large in size, and when cells are small they maintain the benefits of parametric methods and can have lower sampling variance.

We propose a new measure of frictional wage dispersion: the meanmin wage ratio. For a large class of search models, we show that this measure is independent of the wage-offer distribution but depends on statistics of labor-market turnover and on preferences. Under plausible preference parameterizations, observed magnitudes for worker flows imply that in the basic search model, and in most of its extensions, frictional wage dispersion is very small. Notable exceptions are some of the most recent models of on-the-job search. Our new measure allows us to rationalize the diverse empirical findings in the large literature estimating structural search models.

Firms sometimes know more about a consumer's expected usage than the consumer herself. We explore the consequences of this reversal in the information asymmetry. We analyze the consequences of making consumers more informed about themselves. While making consumers more informed decreases their expenditure conditional on a given set of prices, equilibrium prices may increase, offsetting the direct benefit of information. We discuss theoretical and practical issues surrounding so-called RECAP regulation that would require firms to provide each consumer with information about her own usage of the firm's product.

We analyze the effect of search frictions in the market for commercial health insurance. Frictions increase insurance premiums (enough to transfer 13.2 percent of consumer surplus from fully insured employer groups to insurers—approximately $34.4 billion in 1997); and increase insurance turnover (by 64 percent for the average policy). This rent transfer harms consumers and—when combined with heightened turnover—reduces incentives to invest in future health. We also find that a publicly financed insurance option can improve the efficiency of private insurance markets by reducing search friction induced distortions in pricing and marketing efforts.

Halevy (2008) states the equivalence between diminishing impatience (i.e., quasi–hyperbolic discounting) and the common ratio effect. The present paper shows that one way of the equivalence is false and shows the correct and general relationships: diminishing impatience is equivalent to the certainty effect and that strong diminishing impatience (i.e., hyperbolic discounting) is equivalent to the common ratio effect. JEL: D81

A key open question for theories of reference-dependent preferences is: what determines the reference point? One candidate is expectations: what people expect could affect how they feel about what actually occurs. In a real-effort experiment, we manipulate the rational expectations of subjects and check whether this manipulation influences their effort provision. We find that effort provision is significantly different between treatments in the way predicted by models of expectation-based, reference-dependent preferences: if expectations are high, subjects work longer and earn more money than if expectations are low.

We utilize time series tests with structural breaks to test for an adverse impact on economic growth rates in North Africa associated with the recent US financial crisis and global recession. One or two breaks are identified for each country, except for Morocco where no break is found, while breaks coincide with the 2008 financial crisis in only two of the six countries (Libya and Mauritania). These findings suggest that, in general, shocks from the recent financial crisis have only temporary effects on economic growth in these countries. Impulse response functions with breaks confirm these results. We conclude by suggesting explanations for these findings.