Kenneth Massey is an American sports statistician known for his development of a methodology for ranking and rating sports teams in a variety of sports. His ratings have been a part of the Bowl Championship Series since the 1999 season.
Massey, unlike the developers of other sports rating systems, gives quite a lot of information on how his system works, but omits enough details to prevent someone from copying the calculations in their entirety. The Massey Ratings are designed to measure past performance, not necessarily to predict future outcomes. The first challenge for any computer rating system is to account for the variability in performance. A team will not always play up to its full potential. Other random factors (officiating, bounce of the ball) may also affect the outcome of a game. The model must somehow eliminate the "noise" which obscures the true strength of a team. The second goal is to account for the differences in schedule. When there is a large disparity in schedule strength, win-loss records lose their significance. The model must evaluate games involving mismatched opponents, as well as contests between well matched teams. It is necessary to achieve a reasonable balance between rewarding teams for wins, convincing wins, and playing a tough schedule. This issue is difficult to resolve, and rating systems exist that are based on each of the extremes.The overall team rating is a merit based quantity, and is the result of applying a Bayesian win-loss correction to the power rating. Only the score, venue, and date of each game are used to calculate the Massey ratings. Stats such as rushing yards, rebounds, or field-goal percentage are not included. Nor are game conditions such as weather, crowd noise, day/night, or grass/artificial turf. Overtime games are not treated any differently. Finally, neither injuries nor psychological factors like motivation are considered.
Massey's ratings are particularly relevant in the world of American college football, where, with over 100 teams in NCAA Division I competition, there is no way a team can play against more than a small fraction of its competitors. Therefore, in determining the participants in championship games and tournaments, it is necessary to distinguish between teams that have compiled impressive win-loss records against strong competition and teams that have defeated weaker opponents.
In addition, sports rating systems are generally of great interest to gamblers. Massey's ratings have come under some scrutiny as of late 2008 due to his controversial rankings at the end of the season. Although Massey's rating system came under fire near the end of the 2008 season for rating undefeated Utah ahead of then consensus human-poll #1 Alabama, his ratings seemed to be justified following Utah's 31-17 one-sided victory in the 2009 Sugar Bowl.