Other recent research: Nation-state formation | Ethnic exclusion and wars | Ethnic boundary making

Boundaries in social networks: Beyond and below racial homophily

This project puts the boundary making approach to work on the social network data that resulted from a co-operative project with Nicholas Christakis, Jason Kaufman, and Kevin Lewis from the department of sociology at Harvard. We have gathered information on the Facebook.com friendship networks of an entire college freshman class. The project has been featured on the front page of the New York Times and many other news outlets in the US and Europe. A first paper describing the dataset has appeared in Social Networks.

The most often noticed feature of social networks in U.S. society is their high degree of racial homogeneity, which has been attributed to the preference for associating with individuals of the same racial background (i.e. racial homophily). A second paper, co-authored with Kevin Lewis, unpacks racial homogeneity using a theoretical framework that distinguishes between various tie formation mechanisms and their effects on the racial composition of networks, exponential random graph modeling that can disentangle these mechanisms empirically, and a rich new dataset based on the Facebook pages of a cohort of college students. We first show that racial homogeneity results not only from racial homophily proper, but also from homophily among co-ethnics of the same racial background and from balancing mechanisms such as the tendency to reciprocate friendships or to befriend the friends of one’s friends, which both amplify the homogeneity effects of homophily. In a second step, we put the importance of racial homophily further into perspective by comparing its effects to those of other mechanisms of tie formation. Balancing, propinquity based on co-residence, and homophily regarding non-racial categories (such as students from “elite” backgrounds or those hailing from particular states) all influence the tie formation process more than does racial homophily. This paper has been published by the American Journal of Sociology 116(2):583-642, 2010 (click on the link to download the article).