NATIONAL BUREAU OF ECONOMIC RESEARCH
NATIONAL BUREAU OF ECONOMIC RESEARCH

Incapacitation, Concentration, and Juvenile Crime

"Lengthening the school year by one day would lead to a decrease of 0.29 property crimes and an increase of 0.25 violent crimes in a city with a population of 120,000."

Juvenile crime affects millions of people in the United States each year, imposing substantial costs on society. In 1997, 2.8 million people under the age of 18 were arrested, accounting for approximately 20 percent of all arrests. Incarceration of a juvenile is associated with a 10-30 percent decrease in lifetime earnings. The cost to society of allowing one youth to leave high school for a life of crime is estimated to range from $1.7 to $2.3 million.

In Are Idle Hands the Devil's Workshop? Incapacitation, Concentration, and Juvenile Crime (NBER Working Paper No. 9653), Brian Jacob and Lars Lefgren examine the effect of school attendance on juvenile crime. They use data from 29 jurisdictions from 1995-9 collected by the Bureau of Justice Statistics and compiled in the National Incident-Based Reporting System. To this crime data, they add school calendar data for each year, as reported by the corresponding school districts. However, crime may be systemically higher or lower on days when school is not in session for a variety of unrelated reasons. For example, there is evidence that violent crime increases with temperature and on weekends. To address this concern, the authors focus on teacher in-service days - the days on which students do not attend school because teachers are receiving professional training or for planning purposes. Because these days are scattered throughout the school year, they are less likely to be correlated with other factors that may influence juvenile crime.

Jacob and Lefgren find that school attendance appears to reduce the incidence of juvenile property crime by about 15 percent, but increases the level of juvenile crime by nearly 30 percent. They estimate that lengthening the school year by one day would lead to a decrease of 0.29 property crimes and an increase of 0.25 violent crimes in a city with a population of 120,000. Given the average reported value of stolen or damaged property in the study sample of $1,088, the reduction of property crime would result in a savings of approximately $318. However, the total cost of an assault committed by a juvenile is $8,515, making the costs of adding another school day about $2,170, not including the costs associated with processing the case through the criminal justice system.

The authors' findings are consistent with two theories of juvenile crime: the incapacitation and social interaction models. The incapacitation model assumes that when juveniles are provided with structured or monitored activities, they are less likely to engage in anti-social behaviors such as property crime. The social interaction or concentration model assumes that as the concentration of juveniles in a given place increases and they subsequently interact socially more frequently, their involvement in violent crimes increases.

The findings have important implications for after-school youth activities. Proponents of these activities point to the fact that violent crime for teenagers rises during the after-school hours. But, because these programs increase the concentration of young people in certain locations, they run the risk of raising the number of altercations that turn violent. For these programs to be effective, they need to offer structured and monitored activities without substantially increasing the concentration of youth involved.

-- Les Picker


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