Selective incapacitation and the Philadelphia cohort data

The University of Pennsylvania study of delinquency in a Philadelphia birth cohort has been described byNewsweek as perhaps the most influential piece of criminal justice research in the last decade (March 23, 1981). Many have construed the findings as showing that, if imprisonment were focused on the minority of offenders with especially bad prognoses, the rate of crime could be reduced substantially. But others have taken the opposite view that the cohort data, far from endorsing such a selective incapacitation strategy, might actually provide strong evidence that such an approach is futile. Through some further analyses of the Philadelphia data, we attempt to clarify their policy implications.