We analyze delinquent networks of adolescents in the United States. We develop a theoretical model showing who the key player is, i.e. the criminal who once removed generates the highest possible reduction in aggregate crime level. We also show that key players are not necessary the most active...

We develop a dynamic model of identity formation that explains why ethnic minorities may choose to adopt oppositional identities (i.e. some individuals may reject or not the dominant culture) and why this behavior may persist over time. We first show that the prevalence of an oppositional...

We study peer effects in education. We first develop a network model that predicts a relationship between own education and peers’ education as measured by direct links in the social network. We then test this relationship using the four waves of the AddHealth data, looking at the impact of...