Essays on Networks and Migration

Abstract

In the first chapter, we use de-identified data from Facebook to study the nature of peer effects in the market for cell phones. To identify peer effects, we exploit variation in friends' new phone acquisitions resulting from random phone losses. A new phone purchase by a friend has a large and persistent effect on an individual's own demand for phones of the same brand. While peer effects increase the overall demand for phones, a friend's purchase of a particular phone brand can reduce an individual's own demand for phones from competing brands, in particular if they are running on a different operating system. In the second chapter, we analyze de-identified data from Facebook to show how social connections affect beliefs and behaviors in high-stakes settings. During the Covid-19 pandemic, individuals with friends in regions facing severe disease outbreaks reduced their mobility more than their demographically similar neighbors with friends in less affected areas. To explore why social connections shape behaviors, we show that individuals with higher friend exposure to Covid-19 are more supportive of social distancing measures and less likely to advocate to reopen the economy. We conclude that friends influence individuals’ behaviors in part through their beliefs, even when there is abundant information from expert sources. In the third chapter, we use de-identified friendship data from Facebook to study the social integration of Syrian migrants in Germany. We decompose the significant spatial variation in migrants' integration levels into the rate at which Germans befriend their neighbors in general and the particular rate at which they befriend Syrian migrants versus other Germans. We follow the friending behavior of Germans that move across locations to show that both forces are more affected by local institutions and policies than persistent individual characteristics or preferences of local natives. We explore the characteristics of places with higher integration levels, and show that integration courses causally affect place-specific equilibrium integration levels by shifting the rate at which Germans befriend Syrians.