Testing for Racial Differences in the Mental Ability of Young Children

On tests of intelligence, Blacks systematically score worse than Whites, whereas Asians frequently outperform Whites. Some have argued that genetic differences across races account for the gap. Using a newly available nationally representative data set that includes a test of mental function for children aged eight to twelve months, we find only minor racial differences in test outcomes (0.06 standard deviation units in the raw data) between Blacks and Whites that disappear with the inclusion of a limited set of controls. The only statistically significant racial difference is that Asian children score slightly worse than those of other races. To the extent that there are any genetically-driven racial differences in intelligence, these gaps must either emerge after the age of one, or operate along dimensions not captured by this early test of mental cognition.

Measurement Error, Legalized Abortion, and the Decline in Crime: A Response to Foote and Goetz (2005)

Donohue and Levitt (2001) argue that the legalization of abortion in the United States in the 1970s played an important role in explaining the observed decline in crime approximately two decades later. Foote and Goetz (2005) challenge the results presented in one of the tables in that original paper. In this reply, we regretfully acknowledge the omission of state-year interactions in the published version of that table, but show that their inclusion does not alter the qualitative results (or their statistical significance), although it does reduce the magnitude of the estimates. When one uses a more carefully constructed measure of abortion (e.g. one that takes into account cross-state mobility, or doing a better job of matching dates of birth to abortion exposure), however, the evidence in support of the abortion-crime hypothesis is as strong or stronger than suggested in our original work.

Crime, Urban Flight, and the Consequences for Cities

This paper demonstrates that rising crime rates in cities are correlated with city depopulation. Instrumental variables estimates, using measures of the certainty and severity of a state?s criminal justice system as instruments for city crime rates, imply that the direction of causality runs from crime to urban flight. Using annual city-level panel data, our estimates suggest that each additional reported crime is associated with a one person decline in city residents. There is some evidence that increases in suburban crime tend to keep people in cities, although the magnitude of this effect is small. Analysis of individual-level data from the 1980 census confirms the city-level results and demonstrates that almost all of the crime-related population decline is attributable to increased outmigration rather than a decrease in new arrivals to a city. Those households that leave the city because of crime are much more likely to remain within the SMSA than those leaving the city for other reasons. The migration decisions of high-income households and those with children are much more responsive to changes in crime than other households. Crime-related mobility imposes costs on those who choose to remain in the city through declining property values and a shrinking tax base.

The Causes and Consequences of Distinctively Black Names

In the 1960's, Blacks and Whites chose relatively similar first names for their children. Over a short period of time in the early 1970's, that pattern changed dramatically with most Blacks (particularly those living in racially isolated neighborhoods) adopting increasingly distinctive names, but a subset of Blacks actually moving toward more assimilating names. The patterns in the data appear most consistent with a model in which the rise of the Black Power movement influenced how Blacks perceived their identities. Among Blacks born in the last two decades, names provide a strong signal of socio-economic status, which was not previously the case. We find, however, no negative causal impact of having a distinctively Black name on life outcomes. Although that result is seemingly in conflict with previous audit studies involving resumes, we argue that the two sets of findings can be reconciled.

Testing Theories of Discrimination: Evidence from "Weakest Link"

In most settings, it is difficult to measure discrimination, and even more challenging to distinguish between competing theories of discrimination (taste-based versus information-based). Using contestant voting behavior on the television game show Weakest Link, one can in principle empirically address both of these questions. On the show, contestants answer questions and vote off other players, competing for a winner-take-all prize. In early rounds, strategic incentives encourage voting for the weakest competitors. In later rounds, the incentives reverse, and the strongest competitors become the logical target. Controlling for other observable characteristics including the number of correct answers thus far, both theories of discrimination predict that in early rounds, excess votes will be made against groups targeted for discrimination. In later rounds, however, taste-based models predict continued excess votes, whereas statistical discrimination predicts fewer votes against the target group. Empirically, I find some evidence of information-based discrimination towards Hispanics (i.e., other players perceive them as having low ability) and taste-based discrimination against older players (i.e., other players treat them with animus). There is little in the data to suggest discrimination against women and Blacks.

Evaluating the Effectiveness of Child Safety Seats and Seat Belts in Protecting Children from Injury

Young children are required to use child safety seats, and the age threshold at which children can legally graduate to seat belts has steadily increased. This paper tests the relative effectiveness of child safety seats, lap-and-shoulder seat belts, and lap belts in preventing injuries among motor vehicle passengers aged 2-6. We analyze three large, representative samples of crashes reported to police, as well as linked hospital data. We find no apparent difference in the two most serious injury categories for children in child safety seats versus lap-and-shoulder belts. Child safety seats provide a statistically significant 25% reduction in the least serious injury category. Lap belts are somewhat less effective than the two other types of restraints, but far superior to riding unrestrained.

Further Evidence that Legalized Abortion Lowered Crime: A Reply to Joyce

Donohue and Levitt (2001) present a number of analyses that suggest a causal link between legalized abortion and reductions in crime almost two decades later when the cohorts exposed to legalized abortion reach their peak crime years. Joyce (2003) challenges that finding. In this paper, we demonstrate that Joyce's failure to uncover a negative relationship between abortion and crime is a direct consequence of his decision to focus exclusively on the six-year period 1985-90 without including adequate controls for the crack epidemic. We provide empirical evidence that crack hit the high-abortion early legalizing states harder and earlier. We then demonstrate that using precisely the same treatment and control groups as Joyce, but extending the data analysis to encompass the lifetime criminal experiences (as opposed to an arbitrary six-year window), the evidence strongly supports the hypothesis that legalized abortion reduces crime. We also show that our original results are robust to focusing on only the cohorts born immediately before or after Roe v. Wade. The data suggest that ease of access to abortion, rather than simply de jure legalization, is a critical determinant of the extent of the crime reduction.

Market Distortions when Agents are Better Informed: The Value of Information in Real Estate Transactions

Agents are often better informed than the clients who hire them and may exploit this informational advantage. Real-estate agents, who know much more about the housing market than the typical homeowner, are one example. Because real estate agents receive only a small share of the incremental profit when a house sells for a higher value, there is an incentive for them to convince their clients to sell their houses too cheaply and too quickly. We test these predictions by comparing home sales in which real estate agents are hired by others to sell a home to instances in which a real estate agent sells his or her own home. In the former case, the agent has distorted incentives; in the latter case, the agent wants to pursue the first-best. Consistent with the theory, we find homes owned by real estate agents sell for about 3.7 percent more than other houses and stay on the market about 9.5 days longer, even after controlling for a wide range of housing characteristics. Situations in which the agent's informational advantage is larger lead to even greater distortions.

Rotten Apples: An Investigation of the Prevalence and Predictors of Teacher Cheating

We develop an algorithm for detecting teacher cheating that combines information on unexpected test score fluctuations and suspicious patterns of answers for students in a classroom. Using data from the Chicago Public Schools, we estimate that serious cases of teacher or administrator cheating on standardized tests occur in a minimum of 4-5 percent of elementary school classrooms annually. Moreover, the observed frequency of cheating appears to respond strongly to relatively minor changes in incentives. Our results highlight the fact that incentive systems, especially those with bright line rules, often induce behavioral distortions such as cheating. Statistical analysis, however, may provide a means of detecting illicit acts, despite the best attempts of perpetrators to keep them clandestine.