Geography and social links shape economic interactions. In industries, schools, and markets, the entire network determines outcomes. This paper analyzes a large class of games and obtains a striking result. Equilibria depend on a single network measure: the lowest eigenvalue. This paper is the...

Empirical work shows that a large majority of individuals get most of their information from a very small subset of the group, viz., the influencers; moreover, there exist only minor differences between the observable characteristics of the influencers and the others. We refer to these empirical...

We offer a theory of polarization as an optimal response to ambiguity. Suppose individual A's beliefs first-order stochastically dominate individual B's. They observe a common signal. They exhibit polarization if A's posterior dominates her prior and B's prior dominates her posterior. Given...

We model the strategic provision of advice in environments where a principal's optimal action depends on an unobserved, binary state of interest. Experts receive signals about the state and each recommends an action. The principal and all experts dislike making errors in their decision and...

We study the design of informational environments in settings where generating information is costly. We assume that the cost of a signal is proportional to the expected reduction in uncertainty. We show that Kamenica & Gentzkow's (2011) concavification approach to characterizing optimal signals...

We study a uniform-price auction where k identical common-value objects are allocated amongst z k bidders who have imperfect signals about the state of the world. The common valuation is determined jointly by the state and an action that is chosen after winning an object. In large auctions,...

We develop a new methodology to estimate herd behavior in financial markets. We build a model of informational herding that can be estimated with financial transaction data. In the model, rational herding arises because of information-event uncertainty. We estimate the model using data on a NYSE...

The payoff of actions is estimated and the resulting empirical payoff is controlled for in regression analyses to formulate a test of rational expectations in information cascade experiments. We show that the empirical payoff of actions is a function of estimates of choice probabilities and...

A sender may communicate with a decision maker through intermediaries. In this model, an objective sender and intermediary pass on information truthfully, while biased ones favor a particular agenda but also have reputational concerns. I show that the biased sender and the biased intermediary's...