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Are US Crime Rates Really Unit Root Processes?

NCJ Number
237303
Journal
Journal of Quantitative Criminology Volume: 27 Issue: 3 Dated: September 2011 Pages: 299-314
Author(s)
Jemma Cook; Steve Cook
Date Published
September 2011
Length
16 pages
Annotation
This paper examines the nature of crime rate data to provide a characterization of its properties and behaviour, before considering how the results obstained conform with the current understanding of crime available from existing research.
Abstract
Existing research has uncovered little evidence against the hypothesis of U.S. crime rates being unit root processes, despite the uncomfortable implications of this assumption. In light of this, the present paper draws upon noted changes in the temporal patterns of U.S. crime rates since 1960 to undertake an informed approach to testing of the unit root hypothesis which incorporates two potential points of structural change. The results obtained show the unit root hypothesis to be rejected for all classifications of criminal activity examined over the period 1960 to 2007. In addition, the dates of the detected breakpoints are supported by a variety of arguments available in the existing criminology literature concerning alternative determinants of crime and their movements. Interestingly, a difference is observed in the nature of the breaks detected for violent and property crimes. However, potential explanations for this are again found in theoretical arguments available in the criminology literature. Finally, the implications of the current findings for the properties of crime, its subsequent statistical analysis and past and future research are discussed. (Published Abstract)