Homophily in preferences or meetings? Identifying and estimating an iterative network formation model

TL;DR

This paper develops a model to distinguish whether homophily in networks arises from preferences or meeting opportunities, and applies it to Brazilian classroom friendships to evaluate policy impacts.

Contribution

It introduces an iterative network formation model that identifies and estimates the separate effects of preferences and meeting opportunities.

Findings

Preferences have a stronger influence on homophily than meeting opportunities.

Tracking students can improve welfare, especially when preferences dominate.

The benefits of tracking diminish over the school semester.

Abstract

Is homophily in social and economic networks driven by a taste for homogeneity (preferences) or by a higher probability of meeting individuals with similar attributes (opportunity)? This paper studies identification and estimation of an iterative network game that distinguishes between these two mechanisms. Our approach enables us to assess the counterfactual effects of changing the meeting protocol between agents. As an application, we study the role of preferences and meetings in shaping classroom friendship networks in Brazil. In a network structure in which homophily due to preferences is stronger than homophily due to meeting opportunities, tracking students may improve welfare. Still, the relative benefit of this policy diminishes over the school semester.