Illicit Network Evolution and Group Stability

• In Event: Gangs, Co-Offending, and Social Networks Across Space and Time

Abstract

Understanding the evolution of gang membership is central to understanding the persistence of gangs. While some groups persist due to a dynamic supply of offenders who replace high turnover, others persist due to a stable group of offenders who maintain and reproduce the group over time. This variation can be found across criminal groups, gangs or otherwise, yet little is known about the network processes that lead groups to persist. Using data on 10,151 offenders across 187 groups in an urban Canadian city from 1984 to 2011, we examine the structural evolution of offending from their formation to maturation. Our analysis first examines the factors that lead gangs to adopt these structures, applying temporal exponential random graph models to examine the predictors of tie formation across groups. We then turn to the properties of persistence, applying a longitudinal community detection method to measure and predict network stability over time (Palla et al., 2007). The variation in longevity across gangs, allows us to examine rates of membership turnover in relation to the stability of illicit groups. Together these analyses allow us to disentangle the properties of groups who remain stable despite high turnover, and those whose survival depends on stable membership.

Authors

• Marie Ouellet, Simon Fraser University

• Martin Bouchard, Simon Fraser University

• Yanick Charette, Yale University