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Specifying the Relationship Between Crime and Prisons

NCJ Number
222610
Journal
Journal of Quantitative Criminology Volume: 24 Issue: 2 Dated: June 2008 Pages: 149-178
Author(s)
William Spelman
Date Published
June 2008
Length
30 pages
Annotation
This paper applies the best available tests to the best available data in attempting to determine the most appropriate basic specification for equations that measure the effect of imprisonment rates on crime rates and crime rates on imprisonment rates.
Abstract
As expected, increases in prison populations are usually associated with decreases in subsequent crime rates. In addition, increases in crime rates are associated with increases in subsequent prison populations. Thus, crime and prisons apparently are simultaneously determined, and instrument variables are required to separate the effects of one from the other. On a short-term basis, however, violent and property crime rates are largely independent, so there is little harm in using separate equations to determine causes of each crime type. No previous analysis of these variables has adopted this specification in its entirety. This specification strongly suggests that current crime rates and prison populations are the result of an accumulation of many small changes in precursor variables over an extended period of time. Further, there is no long-term equilibrium relationship between crime and prison, only bidirectional causality in the short term. Apart from its technical uses, this specification has implications for thinking about the problem of crime and the primary response to it, i.e., incarceration. The first implication is that a large decrease in the crime rate can only be achieved in small increments over a long period. This implication is explained, along with the implication that crime reduction from imprisonment is related only to the incapacitation of the current prison population, with no deterrent effect on those offenders still active in the community. 11 tables and 70 references