Working Paper No. 617

Who's Who in Crime Networks. Wanted: The Key Player

Publicerad: March 29, 2004Antal sidor: 29Nyckelord: Social Networks; Crime; Centrality Measures; Key Group; PoliciesJEL-koder: A14; C72; K42

Who's Who in Crime Networks. Wanted: The Key Player Coralio Ballester, Antoni Calvó-Armengol and Yves Zenou


Criminals are embedded in a network of relationships. Social ties among criminals are modeled by means of a graph where criminals compete for a booty and benefit from local interactions with their neighbours. Each criminal decides in a non-cooperative way how much crime effort he will exert. We show that the Nash equilibrium crime effort of each individual is proportional to his equilibrium Bonacich-centrality in the network, thus establishing a bridge to the sociology literature on social networks. We then analyze a policy that consists of finding and getting rid of the key player, that is, the criminal who, once removed, leads to the maximum reduction in aggregate crime. We provide a geometric characterization of the key player identified with an optimal inter-centrality measure, which takes into account both a player's centrality and his contribution to the centrality of the others. We also provide a geometric characterization of the key group, which generalizes the key player for a group of criminals of a given size. We finally endogeneize the crime participation decision, resulting in a key player policy, which effectiveness depends on the outside opportunities available to criminals.

 

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