From a review of "Freakonomics" by economist Steve Levitt:
http://www.dailysouthtown.com/southtown/dsnews/0820nd4.htm
See also:
http://tigerhawk.blogspot.com/2005/05/freakonomics-mini-excerpt-incentive-to.html
http://www.freakonomics.com/blog.php
http://www.dailysouthtown.com/southtown/dsnews/0820nd4.htm
I flipped through it at the bookstore and skimmed this section. Basically, he compared rematch rates and found that wins were not coming at the predicted rate, hinting at pro-wrestling style, or at least quid pro quo, manipulation of the outcomes.Levitt co-authored a study that analyzed the won-loss records of sumo wrestlers in tournaments and concluded the matches were rigged. Levitt says he didn't hear a peep from the Japanese press even after sending the findings to the Japanese version of the National Enquirer, which had written about corruption in the sport.
See also:
http://tigerhawk.blogspot.com/2005/05/freakonomics-mini-excerpt-incentive-to.html
http://www.freakonomics.com/blog.php