Knowledge that Transforms

We examine Popper's falsifiability within an economic model in which a tester hires a potential expert to produce a theory. Payments are contingent on the performance of the theory vis-à-vis data. We show that if experts are strategic, falsifiability has no power to distinguish scientific theories from worthless theories. The failure of falsification in screening informed and uninformed experts motivates questions on the broader concepts of refutation and verification. We demonstrate an asymmetry between the two concepts. Like falsification, verification contracts have no power to distinguish between informed and uninformed experts, but some refutation contracts are capable of screening experts. (JEL B41)

The financial crisis has brought a new focus on the accuracy of credit rating agencies (CRAs). In this paper, we highlight the incentives of analysts at the CRAs to provide accurate ratings. We construct a model in which analysts initially work at a CRA and can then either remain or move to a bank. The CRA uses incentive contracts to motivate analysts, but does not capture the benefits if the analyst moves. We find that rating agency accuracy increases with CRA monitoring, bank profitability (a positive “revolving door” effect), and can be non-monotonic in the probability of an analyst leaving.

Merger simulations are commonly used to simulate the effects of potential mergers. Despite the large resources devoted to merger review, little evidence exists on the accuracy of these methods. This paper uses the acquisition of Tambrands by Proctor and Gamble to provide evidence on the efficacy of merger simulation. Two simple demand systems are estimated under several identification assumptions and combined with a static model of price competition. Simulations predict small price effects of about 1 percent for the merging firms' brands, while direct estimates indicate the merger raised prices by 5–8 percent.

In an article published in the American Economic Review, Dorothe Bonjour et al. (2003) used a dataset on female monozygotic twins and showed that the within-twin estimated return to one year of education was 7.7 percent and statistically significant at the 5 percent level. This comment illustrates that the point estimate conclusion is driven by one twin pair, which is an outlier in the dataset. If one eliminates this twin pair, then the estimated return to education is 5.1 percent and statistically significant at the 10 percent level only. (JEL I21, J16, J24, J31)

Each year, more than 250 students in the Chicago Public Schools (CPS) are shot. The authors of this paper worked with the leadership of CPS to build a predictive model of shootings that helped determine which students would be included in a highly targeted and resource intensive mentorship program. This paper describes our predictive model and offers a preliminary evaluation of the mentoring intervention performed by Youth Advocate Programs, Inc. (YAP). We find little evidence that the intervention reduces school misconducts or improves educational outcomes. The scale of intervention was too small to generate meaningful findings on shootings.

We present and discuss preliminary evidence suggesting that credit ratings significantly influenced prices for subprime mortgage-backed securities issued in the period leading up to the recent financial crisis. Ratings are closely correlated with prices even controlling for a rich set of security- and loan-level controls. This incremental variation in ratings has much less predictive power for security defaults, however, based on findings to date from our ongoing research, suggesting prices were excessively sensitive to ratings relative to their informational content.

In the sixteenth century, North America contained 25 to 30 million buffalo; by the late nineteenth century fewer than 100 remained. While removing the buffalo east of the Mississippi took over 100 years, the remaining 10 to 15 million buffalo on the Great Plains were killed in a punctuated slaughter lasting little more than ten years. I employ theory, international trade statistics, and first-person accounts to argue the slaughter was initiated by a foreign-made innovation and fueled by a foreign demand for industrial leather. European demand and American policy failure are jointly responsible for the “Slaughter on the Plains.” (JEL F14, N51, N71, Q57)

Research to date does not demonstrate a causal chain from financial education to welfare-enhancing financial behavior, in part due to biases, heuristics, and emotional influences on decisions. Yet the search for effective financial education continues. But it is time to ask whether giving every person effective financial education would make us better off. Two reasons it might not are discussed here. First, the time, expense, and invasion of privacy required would be enormous. Second, such a world would entail a decrease in individual autonomy. Alternative tools could potentially increase household financial welfare and security at lower social and individual expense.

In the last 15 years, economists and economic historians have argued that Africa has undergone a “reversal of fortune” and that ethnic fragmentation is a significant cause of Africa's underdevelopment. In this article, we join these narratives by arguing that the transatlantic slave trade increased the degree of ethnic heterogeneity in Africa today. Using both correlational and causal instrumental variables analysis, we find an economically and statistically significant positive relationship between slave exports and ethnic heterogeneity. This relationship is robust to changes in the scheme for drawing ethnic boundaries and the choice of observational unit.

We conduct a random-assignment experiment to investigate whether positive affect impacts time preference, where time preference denotes a preference for present over future utility. Our result indicates that, compared to neutral affect, mild positive affect significantly reduces time preference over money. This result is robust to various specification checks, and alternative interpretations of the result are considered. Our result has implications for the effect of happiness on time preference and the role of emotions in economic decision making, in general. Finally, we reconfirm the ubiquity of time preference and start to explore its determinants. (DJEL D12, D83, I31)