Research
Joseph Doyle, MIT Sloan
Published Papers
Nearly 20% of young prison inmates spent part of their youth in foster care. This paper uses the foster care placement frequency of child protection investigators as an instrumental variable to identify causal effects of foster care on adult arrest, conviction, and imprisonment outcomes. A new dataset that links criminal justice data and child abuse investigation data in Illinois allows a comparison of adult crime outcomes across individuals who were investigated for abuse or neglect as children. Families are effectively randomized to child protection investigators through a rotational assignment process, and child characteristics are similar across investigators. Investigator placement frequencies are predictive of subsequent foster care placement, and the results suggest that children who are on the margin of placement are less likely to enter the criminal justice system when they remain at home. One innovation is the examination of the types of children most likely to be marginal cases, and the results suggest that the results apply particularly to girls, African Americans, and children investigated when they are young adolescents.
Evaluating the Effectiveness of Child Safety Seats and Seat Belts in Protecting Children from Injury (Joint with Steven D. Levitt). forthcoming Economic Inquiry
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.
$2.00 Gas! Studying the Effects of a Gas Tax Moratorium. Journal of Public Economics April 2008 (Joint with Krislert Samphantharak)
There are surprisingly few estimates of the effect of sales taxes on retail prices, especially at the firm level. Further, along both sides of a state border, a change in one state's sales tax can shed light on the nature of competition, as a subset of firms effectively experiences a change in its marginal cost. This paper considers the suspension, and subsequent reinstatement, of the 5% gasoline sales tax in Illinois and Indiana following a temporary price spike in the spring of 2000. Earlier laws set the timing of the reinstatements, providing plausibly exogenous changes in the tax rates. Using a unique dataset of daily, gas station-level data, retail gas prices are found to drop by 3% following the suspension, and increase by 4% following the reinstatements. After linking the stations to driving distance data, some evidence suggests that the tax increases are associated with higher prices up to an hour's drive into neighboring states.
The child welfare system investigates over 2 million children each year for parental abuse or neglect, yet little is known about the effects of removing children from home and placing them in foster care. Long-term outcomes are rarely observed, and children placed in foster care likely differ from those not placed, making comparisons difficult. This paper uses the removal tendency of investigators as an instrumental variable to identify causal effects of foster care placement on a range of outcomes for school-age children and youth. A rotational assignment process effectively randomizes families to these investigators. The results suggest that children assigned to investigators with higher removal rates are more likely to be placed in foster care themselves, and they have higher delinquency rates, teen birth rates, and lower earnings. Large marginal treatment effect estimates suggest caution in the interpretation, but the results suggest that children on the margin of placement tend to have better outcomes when they remain at home, especially for older children.
Supplementary Appendix
The Market for Foster
Care: An Empirical Study of the Impact
of Foster Care Subsidies (Joint with H. Elizabeth Peters). Review of Economics of the Household 5(4). December 2007: 329-351.
When parents are suspected of child abuse or neglect, their children may be placed with foster families. We estimate the relationship between the monthly subsidies paid to these families and the quantity of foster care services provided. The empirical model uses variation in subsidies and foster care populations within thirty-seven states and the years 1987-1995. One innovation in our approach is that we exploit the idea that states do not appear to set market clearing rates, as evidenced by a foster home shortage during this time period. In this case of excess demand, variation in the monthly subsidy traces out the supply curve. Our results show that states with high demand may be able to use economic incentives. (Note: the publication is available at www.springerlink.com)
Can’t Buy Me
Love? Subsidizing the Care of
Related Children. Journal of Public Economics 91. February 2007: 281-304.
Little is known about the effect of economic incentives on the willingness to care for relatives, as prices are difficult to measure and typically endogenous. This paper uses a reform in Illinois that reduced the wage offered to relatives asked to provide foster care as a plausibly exogenous change in the cost of caring for related children. Families first contacted just prior to the reform have a substantially higher relative placement rate compared to families contacted after the reform. Children who require mental health services, infants and teenagers appear to be on the margin of relative placement. The estimates are robust to controls, including a sample selection correction that uses the random assignment of investigators to predict entry into the sample. Meanwhile, child health, educational, and placement outcomes do not appear to suffer after the reform. The lower wage may have discouraged those foster parents less interested in child well being, mitigating the effects of the lower subsidy on child outcomes.
Health Insurance, Treatment and Outcomes: Using Automobile Accidents as Health Shocks Review of Economics and Statistics, May 2005, 87(2): 256-270. NBER Working paper version
Previous studies find that the uninsured receive less health care than the insured, yet differences in health outcomes have rarely been studied. In addition, selection bias may partly explain the difference in care received. This paper focuses on an unexpected health shock-severe automobile accidents where victims have little choice but to receive treatment. Another innovation is the use of a comparison group that is similar to the uninsured: those who have private health insurance but do not have automobile insurance. The medically uninsured are found to receive twenty percent less care and have a higher mortality rate compared to patients with health insurance. It appears that the ability-to-pay of patients has a significant effect on treatment decisions and additional treatment yields large improvements in health outcomes.
Working Papers
Returns to Local-Area Emergency Health Care Spending: Using Health Shocks to Patients Far From Home under review. June 2008.
After Midnight: A Regression Discontinuity Design in Length of Postpartum Hospital Stays (with Doug Almond) under review. April 2008.
A rule of thumb in patient billing approximates the length of postpartum hospital stay with the number of midnights spent in the hospital. A newborn delivered at 12:05 a.m. will have an extra night of reimbursable care compared to an infant born minutes earlier. In a dataset of California births from 1991-2002 -- including nearly 100,000 births within 20 minutes of midnight --we find that children born just prior to midnight have significantly shorter lengths of stay than those born just after midnight despite similar observable characteristics. A 1997 law entitling newborns to a minimum stay of two nights allows us to consider two distinct treatments: prior to the 1997 law, the midnight discontinuity typically increased stay length from one to two nights; following the 1997 law, the midnight discontinuity increased stay length from two to three nights. On both margins, we find no effect of stay length on readmissions or mortality for either the infant or the mother, and the estimates are precise. The results suggest that for uncomplicated births, longer hospitals stays incur substantial costs without apparent health benefit.
Returns to Physician Human capital: Analyzing Patients Randomized to Physician Teams (with Todd Wagner & Steven Ewer) under review. July 2008.
Patient sorting can confound estimates of the returns to physician human capital. This paper compares nearly 30,000 patients who were randomly assigned to clinical teams from one of two academic institutions. One institution is among the top medical schools in the country, while the other institution is ranked lower in the quality distribution. Patients treated by the two teams have identical observable characteristics and have access to a single set of facilities and ancillary staff. Those treated by physicians from the higher-ranked institution have 10-25% shorter and less expensive stays than patients assigned to the lower-ranked institution. Health outcomes are not related to the physician team assignment, and the estimates are precise. Procedure differences across the teams are consistent with the ability of physicians in the lower-ranked institution to substitute time and diagnostic tests for the faster judgments of physicians from the top-ranked institution.
Edgeworth Cycles Revisited (with Erich Muehlegger & Krislert Samphantharak) August 2008.
Some gasoline markets exhibit remarkable price cycles, where price spikes are followed by a string of small price declines until the next price spike. This pattern is predicted from a model of competition driven by Edgeworth cycles, as described by Maskin and Tirole. We extend the Maskin and Tirole model and empirically test its predictions with a new dataset of daily station-level prices in 115 US cities. One innovation is that we also examine cycling within cities, which allows controls for city fixed effects. Consistent with the theory, and often in contrast with previous empirical work, we find that the least and most concentrated markets are much less likely to exhibit cycling behavior; and the areas with more independent retailers that have convenience stores are more likely to cycle. We also find that the average gasoline prices are relatively unrelated to cycling behavior.
Employment Effects of a Minimum Wage:
A Density Discontinuity Design Revisited. under revision for resubmission Journal of Applied Econometrics. November 2007.
The minimum wage has a dramatic effect on the wage distribution, and this distortion has been used to estimate large disemployment effects. The main criticism of this approach is its reliance on functional form assumptions. This paper relaxes these assumptions and applies methods commonly used in regression discontinuity designs to this density discontinuity design problem. The estimates suggest that 60% of young workers who would have earned wages below the minimum can no longer find employment, representing roughly 10% of all young people. It appears that large disemployment effects do not stem solely from functional form assumptions. The approach also provides a method to compute the wage distribution in the absence of a minimum wage, and the minimum wage is found to substantially reduce inequality among young workers.
In Progress (various stages)
(Coming Soon) Estimating Marginal Returns to Medical Care: Evidence from Care for At-Risk Newborns (with Doug Almond, Amanda Kowalski and Heidi Williams)
Local-Area variation in Medicare Expenditures & Health Outcomes (with Jon Skinner)
Incarcerating Children: Impacts on Human Capital Accumulation and Labor Market Outcomes (with Anna Aizer).
Household Income Shocks and Child Outcomes: The Case of Mass Layoffs (with Till von Wachter)
Parental Imprisonment & Child Outcomes (with Ilyana Kuziemko)
Hospital Characteristics and Patient Outcomes (with Lorens Helmchen)
Earlier Work Does Lifeline Banking Assist the Unbanked? (with Jose Lopez and Marc Saidenberg). Current Issues in Economics and Finance. June
1998. London’s Size and Diversity: The Advantage in a Competitive World . (with Peter Bancroft, Stephen Glaister,
David Kennedy, and Tony Travers).
London: Corporation of London. January 1996.
Child Welfare Presentation
Presentation to Florida Task Force on Child Protection