MIT Department of Economics : David Abrams : Research Papers

Research Papers

“Understanding High Skill Worker Productivity using Random Case Assignment in a Public Defender’s Office” (Job Market Paper)
Abstract: Measuring high skill worker productivity presents several challenges. High skill workers almost always select their tasks, and unobserved variation across tasks introduces estimation bias. In addition, output for high skill workers is difficult to measure. We exploit a natural experiment where cases are randomly assigned to attorneys within a public defender office to address the selection problem; the random assignment ensures that unobservables have the same distribution across attorneys. Using this data, we are able to investigate the efficiency of the labor market for attorneys, theories of human capital accumulation, and labor market discrimination. Despite a relatively flat wage distribution within cohorts, we find substantial heterogeneity in attorney productivity, as measured by case outcomes. A defendant assigned to a public defender at the 10th percentile of the productivity distribution has an expected sentence length 5.3 months (74% of the mean) longer than the defendant assigned to the public defender at the 90th percentile. Adding attorney fixed effects to a regression of sentence length on case and defendant characteristics doubles the explanatory power. While we do not find any impact of gender or law school quality, Hispanic attorneys in our data set have significantly higher productivity than non-Hispanic attorneys, as do attorneys with greater tenure. These findings suggest that there may be some discrimination in the labor market, and that the positive correlation of wages and tenure is due at least in part to human capital accumulation.

“More Time, Less Crime? Estimating the Deterrent Effect of Incarceration using Sentencing Enhancements” [pdf]

Abstract: Increasing criminal sanctions may reduce crime through two primary mechanisms: deterrence and incapacitation. Disentangling their effects is crucial, since each mechanism has different implications for optimal policy setting. I use the introduction of state add-on gun laws, which enhance sentences for defendants possessing a firearm in the commission of a felony, to isolate the deterrent effect of incarceration. Defendants subject to add-ons would be incarcerated in the absence of the law change, so any short-term impact on crime can be attributed solely to deterrence. Using cross-state variation in the timing of law passage dates, I find that the average add-on gun law results in a roughly 5 percent decline in gun robberies within the first three years of passage. This result is robust to a number of specification tests and does not appear to be associated with large spillovers to other types of crime.

“Do Judges Vary in Their Treatment of Race?”(with Marianne Bertrand and Sendhil Mullainathan) [pdf]
Abstract: Are minorities treated differently by the legal system? Systematic racial differences in case characteristics, many unobservable, make this a difficult question to answer directly. In this paper, we estimate whether judges differ from each other in how they sentence minorities, avoiding potential bias from unobservable case characteristics by exploiting the random assignment of cases to judges. We measure the between-judge variation in the difference in incarceration rates and sentence lengths between African-American and White defendants. We perform a Monte Carlo simulation in order to explicitly construct the appropriate counterfactual, where race does not influence judicial sentencing. In our data set, which includes felony cases from Cook County, Illinois, we find statistically significant between-judge variation in incarceration rates, although not in sentence lengths.

“Optimal Bail and the Value of Freedom: Evidence from the Philadelphia Bail Experiment” (with Chris Rohlfs) [pdf]

Abstract: This paper performs a cost-benefit analysis to determine socially optimal bail levels that balance the costs to defendants against the costs to other members of society. We consider jailing costs, the cost of lost freedom to incarcerated defendants, and the social costs of flight and new crimes committed by released defendants. Using data from a randomized experiment, we estimate the effects of bail amounts on the fraction of defendants posting bail, fleeing, and committing crimes during pre-trial release. We are also able to estimate defendants’ subjective values of freedom by using data on their bail posting decisions. We find that the typical defendant in our sample would be willing to pay roughly $1,000 for 90 days of freedom. Further, judges in our study set bail amounts close to optimum levels even in the absence of bail guidelines.