The Effect of Homophily on Co-Offending Outcomes

Motivation. Apart from weighing the possible benefits and downsides of co-offending, offenders are also facing the problem of partner selection. One aspect of choosing a partner is assigned to homophily, a tendency to connect with partners with similar characteristics. While studies showed that homophily is present in criminal networks, it is still not clear how it affects the co-offending outcomes. The aim of the current study is to explore how similarity-based partner selection affects the structure of criminal networks and consequently the co-offending outcomes, such as the number of co-offenses committed and skills acquired.

Method. We have developed an Agent-Based Model that simulates a population of offenders. Each offender in the simulation chooses a potential partner based on how similar they are to them, also referred to as homophily level. When two offenders select each other, they commit a co-offense and exchange skills. By manipulating the level of homophily in the environment we compared the outcomes of the simulation. Regarding the network structure, we were interested in the number of ties between offenders and the strength of these ties. We used the notion that long-lasting connections are stronger than short-lasting connections.

Results. An increase in the level of homophily results in a larger number of crimes committed by co-offenders, but decreases the skillfulness of agents. Moreover, homophilic networks tend to be clustered with a low number of unique co-offender pairs, but stronger ties between them. On the individual level, agents who have learned the most skills throughout the simulation run are the ones who have the highest degree and sparser egocentric networks.

Conclusion. Homophily level in the environment affects the structure of the network between offenders and consequently the co-offending outcomes. On the one hand, when offenders are exclusive during the partner selection process, they develop long-lasting partnerships, which can be seen as strong ties. This in turn results in a large number of successful crimes committed in the environment, but a low average level of skills acquired by offenders. On the other hand, when offenders are more inclusive, they learn new skills from each other to a greater extent. However, this comes with the consequences of the lower number of co-offenses

Maastricht University, Netherlands