Key Players and Key Groups in Teams: A Network Approach Using Soccer Data

This paper provides a way of evaluating a player's contribution to her team and relates her effort to her salaries. We collect data from UEFA Euro 2008 Tournament and construct the passing network of each team. Then we determine the key player in the game while ranking all the other players too. Next, we identify key groups of players to determine which combination of players played more important role in the match. Using 2010 market values and observable characteristics of the players, we show that players having higher intercentrality measures regardless of their field position have significantly higher market values.Social networks, team game, centrality measures

Revisiting Friendship Networks

We extend the model of friendship networks developed by Brueck- ner (2006) in two ways. First, we extend the level of indirect benefits by incorporating benefits from up to three links and explore its impli- cation for the socially optimal and individual e¤ort levels. Next, we generalize the magnetic agent problem by allowing for more than 3 players by restricting ourselves to regular networks that include pay- o¤s from the magnetic agent.

Enforcement with Costly Group Formation

The joint liability literature claims that positive assortative matching, or risk homogeneity, is always the first best solution. We examine this claim in presence of group formation costs and find that the assertion is not always true.Group Formation Costs

Revisiting Friendship Networks

We extend the model of friendship networks developed by Brueckner (2006) in two ways. First, we extend the level of indirect benefits by incorporating benefits from up to three links and explore its implication for the socially optimal and individual effort levels. Next, we generalize the magnetic agent problem by allowing for more than 3 players by restricting ourselves to regular networks that include payoffs from the magnetic agent.Social networks, Endogenous effort, Magnetic agent

Social Identity and Group Lending

The success of joint liability programs depends on nature and composition of borrowing groups. Group formation is a costly process and in our model these costs vary with the social identity of group partners. We show that risk heterogeneity in a borrowing group may arise due to the social identity of the agents. The presence of caste and gender bias may not resolve the adverse selection and moral hazard problems created by information asymmetry between the borrowers and the lender. We also find that with costly group formation and state verification, individual liability lending may be better than joint liability lending. Thus ignoring social identity and group formation costs can lead to the failure of a joint liability program. Finally, the paper also suggests that targeting different social groups requires the use of a menu of joint liability costs.Group lending; Risk heterogeneity; Formation costs; Social identity

Transport Cost Sharing and Spatial Competition

We consider a linear city model where both firms and consumers have to incur transport costs. Following a standard Hotelling (1929) type framework we analyze a duopoly where firms facing a continuum of consumers choose locations and prices, with the transportation rate being linear in distance. From a theoretical point of view such a model is interesting since mill pricing and uniform delivery pricing arise as special cases. Given the complex nature of the profit function for the two-stage transport cost sharing game, we invoke simplifying assumptions and solve for two different games. We provide a complete characterization for the equilibrium of the location game between the duopolists by removing the price choice from the strategy space. We then find that if the two firms are constrained to locate at the same spot, the resulting price competition leads to a mixed strategy equilibrium with discriminatory rationing. In equilibrium both firms always have positive expected profits. Finally, we derive a pure strategy equilibrium for the two-stage game. Results are then compared with the mill pricing and uniform delivery pricing models.Spatial competition; Cost sharing

Nash Networks with Heterogeneous Agents

A non-cooperative model of network formation is developed. Agents form links with others based on the cost of the link and its assessed benefit. Link formation is one-sided, i.e., agents can initiate links with other agents with- out their consent, provided the agent forming the link makes the appropriate investment. Information flw is two-way. The model builds on the work of Bala and Goyal, but allows for agent heterogeneity. Whereas they permit links to fail with a certain common probability, in our model the probability of failure can be different for different links. We investigate Nash networks that exhibit connectedness and super-connectedness. We provide an explicit characterization of certain star networks. Efficiency and Pareto-optimality issues are discussed through examples. We explore alternative model specifications to address potential shortcomings.