Book

I published a book on Amazon.com which is about this whole enterprise. Ratings, predictions, and college football history are the primary topics, but many others are inter-woven. I never provided a lot of detail on this "about" page because I always intended to write the book. So, the real answers are found there.

However, I took the book offline, as I was not satisfied with the limited formatting capabilities on Amazon's system. Perhaps some day I will bring it out in print.

I'm not terribly excited about the write-up that follows here. I planned on writing the book for years, and thus neglected writing on this site. Then I got more and more wrapped up in gambling advice. The main focus of my work is accurate predictions, and results speaks for themselves. Anyway, if you're looking for some power ratings ideas, the rest of this might be interesting. Others have done a better job on the basic points.

Basics

Two types of power ratings can be found on this site. The first variety is dedicated to making predictions, and almost everything on the site revolves around those ratings. The exception is the historical college football rankings. Those are based on an algorithm similar to the predictive one, but with modifications to compensate for the small number of games played in a college football season, as well as the often very disparite schedule strengths.

Making such a distinction might seem odd, as the very words rate and rank imply orderings related to quality, and thus higher ranked competitors should always be "better" than the lower ranked. However, team quality is a more contentious topic in college football than in any other arena. It has "mythical" national champions, and many seasons have ended with more than one team undefeated.

Thus, the college football ratings for past seasons are a different animal. During an active season, ratings are from the standard predictive model. For finished college football seasons, though, I attempted to create an algorithm that would accurately rank teams, but with concessions to undefeated teams that might not come out #1 by a purely predictive system, and probably deserved recognition as the mythical national champion.

Headaches

That said... There quite simply are no authoritatively "correct" rankings. It takes a while to appreciate this, but after enough study of college football (or any competition), it becomes clear that any team really can win on any given day, and winning a dozen games does not prove a team the "best." There is a tremendous amount of luck involved in football. Twelve games is not a large enough sample to even out the luck - and that is what makes college football rankings an amazing challenge, and one of the most interesting phenomena in all of sports, in my opinion.

I have devoted much time to studying scores over the history of the game. I crafted the system trying to come up with what seemed the best ratings for all seasons. If any team appeared far out of place in any season, I went back to the drawing board and questioned everything. It was a long, frustrating process, but in the end a satisfying experience. I think the ratings are now as close to "right" as can be found, but others must be the judges of that.

The goal is twofold: high quality predictions during the season, and ratings that make sense to most fans at the end of each season. Explaining in detail how this is done would bore most people to tears, so here's a quick summary (that applies to both varieties of ratings):

Quick summary

1. Scores, locations, and dates of games are the data input.
2. Home field advantage adjustments are applied.
3. Power rating values are on a game point scale. Approximate predictions may be made by subtracting a team's power rating from that of its opponent, and then adding 3 points to the home team (4 for basketball). Predictions published on the site are produced through a more complex method.
4. Pre-season ratings are a component of the ratings until about the mid-point of the season.
5. Quoted W-L-T records include only games played against other teams involved in the ratings. If your team is missing a game on its record, it is because the game was against a minor opponent that is not recorded as playing any other team in the rankings that year.
6. For 1977 and later, only Division 1A teams are listed. However, all 1-AA results are included in the calculations.
7. On forfeits: If the game was completed, it is used in the calculations with the score that was recorded. If the game was not completed, then it is completely ignored.

In the ranking lists, the columns "offen" and "defen" give the average points scored and allowed by each team, not including overtimes.

Random Bits

Recent rankings that cause the most headaches are found in 1980, 1997, 1998, and 2002. Those seasons each had at least one major team go undefeated and untied without being dominant in many of their games. The teams are Georgia in 1980, Michigan in 1997, Tennessee in 1998, and Ohio State in 2002. Some of these teams appear ranked as far down as #9 by various ranking systems I have checked over the years. Surely these teams deserve recognition and glory, and yet many mathematical systems fail to give them at least reasonable rankings. I do not think any of these teams should be ranked lower than #3. Happily, Entropy puts two of them at #1 (Tennessee '98 and Ohio State '02). For more on these teams, click here.

Few computer ratings designers completely divulge their method, and for good reason. It is a lot of work to put together an interesting system. Therefore, I believe the best philosophy is to ask visitors to consider the ratings for many past seasons, and judge for themselves which system does the best job.

If the rankings can spotlight some teams that did not get the attention and glory some believed they deserved, I'm happy. On the other hand, some teams are bound to be slighted. I simply point out that this is inevitable, and invite critics to try to do better! ;)

The Entropy CFPOOL confidence values are determined by estimated odds of winning, not predicted margins of victory.

Enjoy, and feel free to send feedback and questions...

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