The selection or seeding of college basketball or football teams for postseason competition

Abstract

Systems for ranking college basketball or football teams take many forms, ranging from polls of selected coaches or members of the media to so-called computer-ranking systems. Some of these are used in ways that have considerable impact on the teams. The committee responsible for the selection and seeding of teams for the postseason National Collegiate Athletic Association (NCAA) Division I men's basketball tournament is influenced by various rankings, including ones based on the ratings percentage index (RPI). The Bowl Championship Series (BCS) rankings of NCAA Division I-A football teams determine which two teams compete in a postseason national championship game and determine eligibility for other prestigious postseason games. There are certain attributes that seem desirable in any ranking system to be used in selecting or seeding teams for postseason competition or that may have some other tangible or intangible effect on the teams. These attributes include accuracy, appropriateness, impartiality, unobtrusiveness, nondisrupliveness, veriflability, and comprehensibility. The polls, the RPI, and the BCS rankings are notably deficient in several of these attributes. A system having all of the attributes, except for unobtrusiveness, can be achieved by applying least squares to a statistical model in which the expected difference in score in each game is modeled as a difference in team effects plus or minus a home court/field advantage. The potential obtrusiveness of this approach can be circumvented by introducing modifications to reward winning per se and to eliminate any incentive for "running up the score" or for deliberately surrendering a lead so as to extend a game into overtime. The modified least squares system was applied to the 1999-2000 basketball and 1999-2001 football seasons. Its accuracy in predicting the outcomes of 73 postseason football games and 93 postseason basketball games was undiminished by the modifications and was comparable to that of the betting line.