Ethnic Homophily and Triad Closure

Abstract

Previous studies indicate the importance of similarities between street gang members in terms of ethnicity for mapping the patterns of co-offending relationships within gangs. Individual members are more likely to co-offend with other members who are from the same ethnicity. Past studies, however, do not appropriately account for the fact that correlation between attributes of co-offending gang members may be driven by alternative mechanisms. Most importantly, the presence of clustering in networks can dramatically affect the assessment and make us believe that homophily—the deliberate choice to co-offend with others from the same ethnic group—is important while in fact it is not. In this article, we recreate the internal structure of a London-based street gang with exponential random graph (ERG) models. Our results refine the role of ethnicity for co-offending within gangs. While homophily is still prevalent, the effect diminishes when triad closure—the tendency for two individuals to offend with each other when they also offend with a common third person—is considered. Furthermore, we extend existing ERG specifications and investigate the interaction between ethnic homophily and triad closure. Findings indicate that ethnic homophily is even stronger when it is embedded in co-offending triads.