Steven D. Levitt

Using Electoral Cycles in Police Hiring to Estimate the Effect of Police on Crime: Comment

Previous empirical studies have typically uncovered little evidence that police reduce crime. One problem with those studies is a failure to adequately deal with the simultaneity between police and crime: while police may or may not reduce crime, there is little doubt that expenditures on police forces are an increasing function of the crime rate. In this study, the timing of mayoral and gubernatorial elections is used to identify the effect of police on crime. This paper first demonstrates that increases in the size of police forces disproportionately occur in mayoral and gubernatorial election years, a relationship that had previously gone undocumented. After controlling for changes in government spending on other social programs, there is little reason to think that elections will be otherwise correlated with crime, making elections ideal instruments. Using a panel of large U.S. cities from 1970-1992, police are shown to reduce crime for six of the seven crime categories examined. Each additional police officer is estimated to eliminate eight to ten serious crimes. Existing estimates of the costs of crime suggest that the social benefit of reduced crime is approximately

Understanding Why Crime Fell in the 1990s: Four Factors that Explain the Decline and Six that Do Not

100,000 per officer per year, implying that the current number of police is below the optimal level.

Understanding the Black-White Test Score Gap in the First Two Years of School

Crime fell sharply in the United States in the 1990s, in all categories of crime and all parts of the nation. Homicide rates plunged 43 percent from the peak in 1991 to 2001, reaching the lowest levels in 35 years. The Federal Bureau of Investigation’ s (FBI) violent and property crime indexes fell 34 and 29 percent, respectively, over that same period. These declines occurred essentially without warning: leading experts were predicting an explosion in crime in the early and mid-1990s, precisely the point when crime rates began to plunge. Although experts failed to anticipate the decline, there has been no shortage of hypotheses to explain the drop in crime after the fact. Table 1 presents a tally of a Lexis-Nexis search of the most frequently cited reasons for the crime decline in articles in major newspapers over the period 1991‐ 2001. The single most frequent explanation given is the innovative policing strategies put into place. The crime decline is also frequently attributed to increased imprisonment, changes in the market for crack cocaine, the aging of the population, tougher gun control laws, the strong economy and increases in the number of police. In this paper, I attempt to sort out why crime declined in the 1990s. I begin with a review of the facts. I then analyze the leading explanations for why crime fell, looking at possible determinants that changed in some substantial way in the 1990s. Most of the supposed explanations listed in Table 1 actually played little direct role in the crime decline, including the strong economy of the 1990s, changing demographics, better policing strategies, gun control laws, concealed weapons laws and increased use of the death penalty. Four factors, however, can account for virtually

The Effect of Prison Population Size on Crime Rates: Evidence from Prison Overcrowding Litigation

In previous research, a substantial gap in test scores between white and black students persists, even after controlling for a wide range of observable characteristics. Using a newly available data set (the Early Childhood Longitudinal Study), we demonstrate that in stark contrast to earlier studies, the black-white test score gap among incoming kindergartners disappears when we control for a small number of covariates. Real gains by black children in recent cohorts appear to play an important role in explaining the differences between our findings and earlier research. The availability of better covariates also contributes. Over the first two years of school, however, blacks lose substantial ground relative to other races. There is suggestive evidence that differences in school quality may be an important part of the explanation. None of the other hypotheses we test to explain why blacks are losing ground receive any empirical backing.

Crime, Urban Flight, and the Consequences for Cities

Previous studies of the impact of changes in prisoner populations on crime rates have failed to adequately control for the simultaneity between those two variables. While increases in the number of prisoners are likely to reduce crime, rising crime rates also translate into larger prison populations. To break that simultaneity, this paper uses the status of prison overcrowding litigation in a state as an instrument for changes in the prison population. Overcrowding litigation is demonstrated to have a negative impact on prison populations, but is unlikely to be related to fluctuations in the crime rate, except through its effect on prison populations. Instrumenting results in estimates of the elasticity of crime with respect to the number of prisoners that are two to three times greater than previous studies. The results are robust across all of the crime categories examined. For each one-prisoner reduction induced by prison overcrowding litigation, the total number of crimes committed increases by approximately 15 per year. The social benefit from eliminating those 15 crimes is approximately

Political Parties and the Distribution of federal Outlays

45,000; the annual per prisoner costs of incarceration are roughly

The Impact of Federal Spending on House Election Outcomes

30,000.

Comparing Interest Group Scores across Time and Chambers: Adjusted ADA Scores for the U.S. Congress

This paper analyzes the link between rising city crime rates and urban flight. Each additional reported crime is associated with a roughly one-person decline in city population. Almost all of the crime-related population decline is attributable to increased out-migration rather than a decrease in new arrivals. Households that leave the city because of crime are much more likely to remain within the Standard Metropolitan Statistical Area (SMSA) than those that leave the city for other reasons. Migration decisions of highly educated households and those with children are particularly responsive to changes in crime. Causality appears to run from rising crime rates to city depopulation.

Winning Isn't Everything: Corruption in Sumo Wrestling

Theory: Several models of distributive politics predict a role for parties in determining the allocation of federal outlays. Hypotheses: The number of Democratic voters will be positively correlated with federal outlays, even after controlling for demographic and socioeconomic variables. The degree to which a program will be skewed to Democrats will be a function of the amount of variation in program benefits across districts, whether the program is administered by formula, and the extent of one-party control when the program is initiated. Methods: Regression analysis of district-level data on election outcomes and federal assistance programs for the period 1984-90. Results: The number of Democratic voters is an important predictor of the amount of federal dollars flowing to a district. Programs with a greater amount of variation across districts are more heavily skewed to Democrats, as are programs administered by formula. Programs initiated in the latter half of the 1970s, a time of solid Democratic control, exhibit the greatest bias towards Democrats; programs started in the Reagan era show no such bias. Our results are consistent with a model in which parties in the United States play an important, but limited role in determining the distribution of federal dollars: given enough time, parties can target types of voters, but they cannot easily target specific districts.

Decomposing the Sources of Incumbency Advantage in the U. S. House

While it is widely believed by academics, politicians, and the popular press that incumbent members of Congress are rewarded by the electorate for bringing federal dollars to their district, the empirical evidence supporting that claim is extremely weak. One explanation for the failure to uncover the expected relationship between federal spending and election outcomes is that incumbents who expect to have difficulty being reelected are likely to exert greater effort in obtaining federal outlays. Since it is generally impossible to adequately measure this effort, the estimated impact of spending is biased downward because of an omitted variable bias. We address this estimation problem using instrumental variables. For each House district, we use spending outside the district but inside the state containing the district as an instrument for spending in the district. Federal spending is affected by a large number of actors (e.g., governors, senators, mayors, and other House members in the state delegation), leading to positive correlations in federal spending across the House districts within states. However, federal spending outside of a district is unlikely to be strongly correlated with the strength of that districts electoral challenge. In contrast to previous studies, we find strong evidence that federal spending benefits congressional incumbents: an additional