2007 BCS computer rankings
Encyclopedia
The 2007 BCS computer rankings are a part of the Bowl Championship Series
(BCS) formula that determines who plays in the BCS National Championship Game
as well as several other bowl game
s. Each computer system was developed using different methods which attempts to rank the teams performance. For 2007, the highest and lowest rankings for a team are dropped and the remaining four rankings are summed. A team ranked #1 by a computer system is given 25 points, #2 is given 24 points and so forth. The summed values are then divided by 100 (the maximum value a team can earn if they received four first place votes that were summed). The values are then ranked by percentage. This percentage ranking is then averaged with the Coaches Poll
and Harris Poll average rankings, each receiving equal weight, and the results become the BCS Rankings.
It should be noted that the BCS once allowed computer rankings to consider margin of victory, but was removed following the 2004 season. Therefore, all six computer systems currently do not include margin of victory. However, this computer system has never included it in its formula. In addition, only human polls (specifically the AP Poll
and Coaches Poll
in this reference) "prejudge" teams by releasing pre-season polls with the expected rankings of teams before they have played any games. The last two claims are subjective opinions by the authors of this computer system.
Billingsley did use margin of victory, but removed it after the 2001 season. It had accounted for 5% of the total ranking for his system and was part of it for 32 years. Also, this computer system releases rankings each week, using a complex formula to incorporate the previous season's rank (but not ranking score) into the early parts of the current season.
in Astrophysical Sciences. He attended Virginia and is therefore a Virginia fan. His brother, Will Colley played for Georgia. Colley claims 5 advantages using his system:
While all computer systems are not biased towards the "Name recognition" of a school, Colley's system doesn't include any information that doesn't involve the current season. No pre-season poll and no carry-over from the previous season.
is the owner of this complex computer system. He was a Ph.D candidate of Mathematics at Virginia Tech. Only the score, venue, and date of each game are used to calculate the Massey ratings. However, Massey calculates an offensive and defensive ratings which combine to produce a power ranking as well. The overall team rating is a merit based quantity, and is the result of applying a Bayesian
win-loss correction to the power rating.
owns this computer system that is published in USA Today
. He holds an MBA from Indiana. This system uses the Elo Chess system
where winning and losing are the sole factors. He also publishes a "Predictor" system that uses margin of victory. However, the BCS only uses the Elo Chess system.
uses a Bradley-Terry model
for his computer system. It uses wins and losses but also uses game location as a factor. In addition, he ranks all teams that can be connected by schedule played (over 700 involving Division I FBS, Division I FCS, II, III and NAIA
).
Bowl Championship Series
The Bowl Championship Series is a selection system that creates five bowl match-ups involving ten of the top ranked teams in the NCAA Division I Football Bowl Subdivision , including an opportunity for the top two to compete in the BCS National Championship Game.The BCS relies on a combination of...
(BCS) formula that determines who plays in the BCS National Championship Game
BCS National Championship Game
The BCS National Championship Game, or BCS National Championship, is the final bowl game of the annual Bowl Championship Series and is intended by the organizers of the BCS to determine the U.S. national champion of the NCAA Division I Football Bowl Subdivision...
as well as several other bowl game
Bowl game
In North America, a bowl game is commonly considered to refer to one of a number of post-season college football games. Prior to 2002, bowl game statistics were not included in players' career totals and the games were mostly considered to be exhibition games involving a payout to participating...
s. Each computer system was developed using different methods which attempts to rank the teams performance. For 2007, the highest and lowest rankings for a team are dropped and the remaining four rankings are summed. A team ranked #1 by a computer system is given 25 points, #2 is given 24 points and so forth. The summed values are then divided by 100 (the maximum value a team can earn if they received four first place votes that were summed). The values are then ranked by percentage. This percentage ranking is then averaged with the Coaches Poll
Coaches Poll
The USA Today Coaches' Poll is the current name for a weekly ranking of the top 25 NCAA Division I Football Bowl Subdivision college football and Division I college basketball teams....
and Harris Poll average rankings, each receiving equal weight, and the results become the BCS Rankings.
BCS computer rankings average
For 2007, the rankings released beginning with the eighth week of the season on October 13. The rankings are updated each week until the end of the season. Data taken from official BCS website. There are missing values in the table because the BCS Rankings only list the top 25 of the BCS Rankings, providing data on how those teams achieved their top 25 ranking. The computers ranking may include teams that do not make the top 25 BCS Rankings once averaged with the AP and Coaches Polls.Anderson & Hester
Jeff Anderson and Chris Hester are the owners of this computer system that has been a part of the BCS since its inception. The Anderson & Hester Rankings claim to be distinct in four ways:- These rankings do not reward teams for running up scores. Teams are rewarded for beating quality opponents, which is the object of the game. Margin of victory, which is not the object of the game, is not considered.
- Unlike the AP and Coaches Polls, these rankings do not prejudge teams. These rankings first appear after the season's fifth week, and each team's ranking reflects its actual accomplishments on the field, not its perceived potential.
- These rankings compute the most accurate strength of schedule ratings. Each team's opponents and opponents' opponents are judged not only by their won-lost records but also, uniquely, by their conferences' strength (see #4).
- These rankings provide the most accurate conference ratings. Each conference is rated according to its non-conference won-lost record and the difficulty of its non-conference schedule.
It should be noted that the BCS once allowed computer rankings to consider margin of victory, but was removed following the 2004 season. Therefore, all six computer systems currently do not include margin of victory. However, this computer system has never included it in its formula. In addition, only human polls (specifically the AP Poll
AP Poll
The Associated Press College Poll refers to weekly rankings of the top 25 NCAA teams in one of three Division I college sports: football, men's basketball and women's basketball. The rankings are compiled by polling sportswriters across the nation...
and Coaches Poll
Coaches Poll
The USA Today Coaches' Poll is the current name for a weekly ranking of the top 25 NCAA Division I Football Bowl Subdivision college football and Division I college basketball teams....
in this reference) "prejudge" teams by releasing pre-season polls with the expected rankings of teams before they have played any games. The last two claims are subjective opinions by the authors of this computer system.
Billingsley
Richard Billingsley owns this computer system. He describes himself as not a mathematician or computer-geek; simply a devout college football fan since the age of 7. The main components in the formula are: Won-Loss Records, Opponent Strength (based on the opponent’s record, rating, and rank), with a strong emphasis on the most recent performance. Very minor consideration is also given to the site of the game, and defensive scoring performance.Billingsley did use margin of victory, but removed it after the 2001 season. It had accounted for 5% of the total ranking for his system and was part of it for 32 years. Also, this computer system releases rankings each week, using a complex formula to incorporate the previous season's rank (but not ranking score) into the early parts of the current season.
Colley Matrix
Wes Colley has a Ph.D from Princeton UniversityPrinceton University
Princeton University is a private research university located in Princeton, New Jersey, United States. The school is one of the eight universities of the Ivy League, and is one of the nine Colonial Colleges founded before the American Revolution....
in Astrophysical Sciences. He attended Virginia and is therefore a Virginia fan. His brother, Will Colley played for Georgia. Colley claims 5 advantages using his system:
- First and foremost, the rankings are based only on results from the field, with absolutely no influence from opinion, past performance, tradition or any other bias factor. This is why there is no pre-season poll here. All teams are assumed equal at the beginning of each year.
- Second, strength of schedule has a strong influence on the final ranking. A team does not gain by padding its schedule, so those wins against James Madison or William & Mary are discounted. (Prior to 2007, these games were completely ignored. With the schedule expansion to 12 games, these are now counted but still influence the scores very little since their strength of schedule makes them very weak teams.) For example, Wisconsin with 4 losses finished the 2000 season well ahead of TCU with only 2 losses. That's because Wisconsin's Big 10 schedule was much, much more difficult that TCU's WAC schedule.
- Third, as with the NFL, NHL, NBA, and Major League, score margin does not matter at all in determining ranking, so a large victory margin may influence pollsters, but does not influence this scheme. This reflects Colley's view that the object of football is winning the game, not winning by a large margin.
- Fourth, there is no ad hoc weighting of opponents' winning percentage and opponents' opponents' winning percentage, etc., ad infinitum (no random choices of 1/3 of this + 2/3 of that, for example). In this method, very simple statistical principles, with absolutely no fine tuning are used to construct a system of 117 equations with 117 variables, representing each team according only to its wins and losses, (see Ranking Method). The computer simply solves those equations to arrive at a rating (and ranking) for each team.
- Fifth, comparison between this scheme and the final press polls (1998, 1999, 2000, 2001, 2002) proves that the scheme produces sensible results.
While all computer systems are not biased towards the "Name recognition" of a school, Colley's system doesn't include any information that doesn't involve the current season. No pre-season poll and no carry-over from the previous season.
Massey
Kenneth MasseyKenneth Massey
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...
is the owner of this complex computer system. He was a Ph.D candidate of Mathematics at Virginia Tech. Only the score, venue, and date of each game are used to calculate the Massey ratings. However, Massey calculates an offensive and defensive ratings which combine to produce a power ranking as well. The overall team rating is a merit based quantity, and is the result of applying a Bayesian
Bayesian probability
Bayesian probability is one of the different interpretations of the concept of probability and belongs to the category of evidential probabilities. The Bayesian interpretation of probability can be seen as an extension of logic that enables reasoning with propositions, whose truth or falsity is...
win-loss correction to the power rating.
Sagarin
Jeff SagarinJeff Sagarin
Jeff Sagarin is an American sports statistician well-known for his development of a methodology for ranking and rating sports teams in a variety of sports...
owns this computer system that is published in USA Today
USA Today
USA Today is a national American daily newspaper published by the Gannett Company. It was founded by Al Neuharth. The newspaper vies with The Wall Street Journal for the position of having the widest circulation of any newspaper in the United States, something it previously held since 2003...
. He holds an MBA from Indiana. This system uses the Elo Chess system
Elo rating system
The Elo rating system is a method for calculating the relative skill levels of players in two-player games such as chess. It is named after its creator Arpad Elo, a Hungarian-born American physics professor....
where winning and losing are the sole factors. He also publishes a "Predictor" system that uses margin of victory. However, the BCS only uses the Elo Chess system.
Wolfe
Peter WolfePeter Wolfe (Sports Rankings)
Peter R. Wolfe is the owner of a computer system that is used by the Bowl Championship Series to rank collegiate football teams.-External links:*...
uses a Bradley-Terry model
Pairwise comparison
Pairwise comparison generally refers to any process of comparing entities in pairs to judge which of each entity is preferred, or has a greater amount of some quantitative property. The method of pairwise comparison is used in the scientific study of preferences, attitudes, voting systems, social...
for his computer system. It uses wins and losses but also uses game location as a factor. In addition, he ranks all teams that can be connected by schedule played (over 700 involving Division I FBS, Division I FCS, II, III and NAIA
National Association of Intercollegiate Athletics
The National Association of Intercollegiate Athletics is an athletic association that organizes college and university-level athletic programs. Membership in the NAIA consists of smaller colleges and universities across the United States. The NAIA allows colleges and universities outside the USA...
).
Legend
| Increase in ranking | ||
| Decrease in ranking | ||
| Not ranked previous week | ||
| Italics | Number of first place votes | |
| (#-#) | Win-loss record | |
| (t) | Tied with team above or below also with this symbol |