An Economic Model of Friendship: Homophily, Minorities, and Segregation
构建了一个友谊形成模型，解释社会和经济网络中观察到的隔离模式，并分析群体规模如何影响同类型友谊的偏向。
We develop a model of friendship formation that sheds light on segregation patterns observed in social and economic networks. Individuals have types and see type-dependent benefits from friendships. We examine the properties of a steady-state equilibrium of a matching process of friendship formation. We use the model to understand three empirical patterns of friendship formation: (i) larger groups tend to form more same-type ties and fewer other-type ties than small groups, (ii) larger groups form more ties per capita, and (iii) all groups are biased towards same-type relative to demographics, with the most extreme bias coming from middle-sized groups. We show how these empirical observations can be generated by biases in preferences and biases in meetings. We also illustrate some welfare implications of the model. Copyright 2009 The Econometric Society.