two months. Furthermore, each wrestler belongs to a stable that is typi- cally managed by a former sumo champion, so even the rival stables have close ties. (Wrestlers from the same stable do not wrestle one an- other.) Now lets look at the win-loss percentage between the 7-7 wrestlers and the 8-6 wrestlers the next time they meet, when neither one is on the bubble. In this case, there is no great pressure on the in- dividual match. So you might expect the wrestlers who won their 7-7 matches in the previous tournament to do about as well as they had in earlier matches against these same opponents-that is, winning roughly 50 percent of the time. You certainly wouldnt expect them to uphold their 80 percent clip.     As it turns out, the data show that the 7-7 wrestlers win only 40 percent of the rematches. Eighty percent in one match and 40 percent in the next? How do you make sense of that? The most logical explanation is that the wrestlers made a quid pro quo agreement: you let me win today, when I really need the victory, and Ill let you win the next time. (Such an arrangement wouldnt pre- clude a cash bribe.) Its especially interesting to note that by the two wrestlers second subsequent meeting, the win percentages revert to the expected level of about 50 percent, suggesting that the collusion spans only two matches. And it isnt only the individual wrestlers whose records are suspect. The collective records of the various sumo stables are similarly aberra- tional. When one stables wrestlers fare well on the bubble against wrestlers from a second stable, they tend to do especially poorly when the second stables wrestlers are on the bubble. This indicates that some match rigging may be choreographed at the highest level of the sport-much like the Olympic skating judges vote swapping. No formal disciplinary action has ever been taken against a Japa- nese sumo wrestler for match rigging. Officials from the Japanese