In sumo wrestling, a wrestler's ranking determines every aspect of his life. Rankings are determined by the number of wins at bimonthly tournaments. An unusually high number of wrestlers with a 7-7 record go on to win in their final bout, enabling them to advance. There are theories that economic incentives could be involved, with higher-ranked wrestlers being bribed to throw a fight in favor of a competitor who would otherwise not advance. However, in the sumo community, there are also strong moral and social incentives for the higher-ranked wrestlers to assist those at risk of falling back in the rankings.
Author Steven Levitt, working with journalist Stephen Dubner, shows how economic theories can be use...
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