In this paper, we investigate the impact of peers on own outcomes where all agents embedded in a network choose more than one activity. We develop a simple network model that illustrates these issues. We differentiate between the ‘seemingly unrelated’ simultaneous equations model where...

There is substantial empirical evidence showing that peer effects matter in many activities. The workhorse model in empirical work on peer effects is the linear-in-means (LIM) model, whereby it is assumed that agents are linearly affected by the mean action of their peers. We provide two...

We develop a network model of conflict in which players are involved in different battles. A negative shock in one locality affects the conflict in this locality but may also increase battles in path-connected localities depending on the location of the battle in the network and the strength of...

Although the linear-in-means model is the workhorse model in empirical work on peer effects, its theoretical properties are understudied. In this paper, we investigate how social norms affect individual effort, aggregate effort, and welfare. While individual productivity always positively...

We survey the literature on social networks by putting together the economics, sociological and physics/applied mathematics approaches, showing their similarities and differences. We expose, in particular, the two main ways of modeling network formation. While the physics/applied mathematics...

We study a structural model of R&D alliance networks in which firms jointly form R&D collaborations to lower their production costs while competing on the product market. We derive the Nash equilibrium of this game, provide a welfare analysis and determine the optimal R&D subsidy program that...

We develop a model where the unemployed workers in the city can find a job either directly or through weak or strong ties. We show that, in denser areas, individuals choose to interact with more people and meet more random encounters (weak ties) than in sparsely populated areas. We also...

We consider a model where each individual (or ethnic minority) is embedded in a network of relation-ships and decides whether or not she wants to be assimilated to the majority norm. Each individual wants her behavior to agree with her personal ideal action or norm but also wants her behavior to...

We consider a network model where individuals exert efforts in two types of activities that are interdependent. These activities can be either substitutes or complements. We provide a full characterization of the Nash equilibrium of this game for any network structure. We show, in particular,...

There is substantial empirical evidence showing that peer effects matter in many activities. The workhorse model in empirical work on peer effects is the linear-in-means (LIM) model, whereby it is assumed that agents are linearly affected by the mean action of their peers. We develop a new...