We model social media as collections of users producing and consuming content. Users value consuming content, but doing so uses up their scarce attention, and hence they prefer content produced by more able users. Users also value receiving attention, creating the incentive to attract an...

Using newly validated data on geographic migration networks, we study how labor demand shocks in the United States propagate across the border with Mexico. We show that the large exogenous decline in US employment brought about by the Great Recession affected demographic and economic outcomes in...

We analyze the diffusion of rival information in a social network. In our model, rational agents can share information sequentially, unconstrained by an exogenous protocol or timing. We show how to compute the set of eventually informed agents for any network, and show that it is essentially...

We present a model of online content sharing where agents sequentially observe an article and must decide whether to share it with others. The article may contain misinformation, but at a cost, agents can fact-check it to determine whether its content is entirely accurate. While agents derive...

An information cascade is a situation in which an agent who observes others chooses the same action irrespective of the value of the agent's private information signal. Theoretical models have found that cascades result in poor information aggregation, inaccurate decisions, and fragility of mass...

We use de-identified data from Facebook to study the social integration of Syrian migrants in Germany, a country that received a large influx of refugees during the Syrian Civil War. We construct measures of migrants' social integration based on Syrians' friendship links to Germans, their use of...

This paper uses the concept of the triad census first introduced by Holland and Leinhardt, and describes several distributions on directed graphs. Methods are presented for calculating the mean and the covariance matrix of the triad census for the uniform distribution that conditions on the...

We introduce the concept of a triad census of a digraph arid show how it can be used to enumerate various types of subgraph configurations. We give the basic probabilities needed for computing means and variances for a triad census under the U-MAN distribution for digraphs. These concepts are...

Entrepreneurs, particularly in the developing world, often hire from their networks: friends, family, and resulting referrals. Network hiring has two benefits, documented extensively in the empirical literature: entrepreneurs know more about the ability of their network (and indeed they are...

We use anonymized and aggregated data from Facebook to explore the spatial structure of social networks in the New York metro area. We highlight the importance of transportation infrastructure in shaping urban social networks by showingthat travel time and travel costs are substantially stronger...