Who´s Who in Networks. Wanted: The Key Player

Reprint No. 2006:14

Author(s): Coralio Ballester, Antoni Calvó-Armengol and Yves ZenouYear: 2006 Title: Econometrica Volume (No.): 74 (5) Pages: 1403–1417

Finite population noncooperative games with linear-quadratic utilities, where each player decides how much action she exerts, can be interpreted as a network game with local payoff complementarities, together with a globally uniform payoff substitutability component and an own-concavity effect. For these games, the Nash equilibrium action of each player is proportional to her Bonacich centrality in the network of local complementarities, thus establishing a bridge with the sociology literature on social networks. This Bonacich–Nash linkage implies that aggregate equilibrium increases with network size and density. We then analyze a policy that consists of targeting the key player, that is, the player who, once removed, leads to the optimal change in aggregate activity. We provide a geometric characterization of the key player identified with an intercentrality measure, which takes into account both a player’s centrality and her contribution to the centrality of the others.

Ballester, Coralio, Antoni Calvó-Armengol and Yves Zenou (2006), "Who´s Who in Networks. Wanted: The Key Player". Econometrica 74(5), 1403–1417.

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Martin Ljunge, IFN, is the author of a chapter, "Trust promotes health: addressing reverse causality by studying children of immigrants", in a new book edited by Sherman Folland and Eric Nauenberg. The cutting edge of research is presented, covering the ever-expanding social capital field.

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