دانلود رایگان مقاله اندازه گیری تاثیرات تکرار در شبکه اجتماعی جنایی

Abstract

The ‘‘near-repeat” effect is a well-known criminological phenomenon in which the occurrence of a crime incident gives rise to a temporary elevation of crime risk within close physical proximity to an initial incident. Adopting a social network perspective, we instead define a near repeat in terms of geodesic distance within a criminal social network, rather than spatial distance. Specifi- cally, we report a statistical analysis of repeat effects in arrest data for Chicago during the years 2003–2012. We divide the arrest data into two sets (violent crimes and other crimes) and, for each set, we compare the distributions of time intervals between repeat incidents to theoretical distributions in which repeat incidents occur only by chance. We first consider the case of the same arrestee participating in repeat incidents (‘‘exact repeats”) and then extend the analysis to evaluate repeat risks of those arrestees near one another in the social network. We observe repeat effects that diminish as a function of geodesic distance and time interval, and we estimate typical time scales for repeat crimes in Chicago.

4. Conclusion

This work is motivated by our interest in identifying factors that may be predictive of an individual’s involvement in future violence to enhance the predictive models we have developed as part of the Chicago Police Department’s predictive policing program. Specifically, we have developed a very successful prediction model that evaluates the crime risk of individuals with very severe patterns of involvement in crime. This paper demonstrates conclusively that an individual’s crime risk increases for a period of roughly 25 weeks (about 6 months) following a crime involving a person within two or less degrees of separation from an individual involved in that crime. To make practical use of this finding, we are currently in the process of revising our prediction model by including new variables pertaining to first- and second-degree connections, as well as a weighting function that gives greater emphasis to the effect of recent crime incidents, as opposed to those in the more distant past. In addition to the practical significance for our current project, the findings of this paper provide us with fundamental insights about patterns of crime and its temporal and interpersonal behavior, for both violent and non-violent crime types. In this work, to test f