J-Train Computer Rankings

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This week I will be debuting my FBS computer rankings. Creating a ranking system is something I’ve wanted to try for a long time. The math is very simple but I believe I’ve implemented the basic value system that I had hoped for. I was influenced by and share essentially the same core concepts as the late David Rothman. (I’m interested to see if my system produces similar results to his over time.)

  • The system is retrodictive. The point is to determine the quality of a team’s “resumé” rather than to predict future games.
  • The system is win-centric. A win is almost always worth more than a loss, with the exceptions involving close wins over very bad teams and close losses to great teams.
  • Margin of victory counts, although the returns are diminishing. The rating increase from a one-point win to a 15-point win is substantial and considerably higher than the increase from a 21-point win to a 35-point win. The increase in margin from 51 to 65 is essentially negligible. It has been said that the point of the game is simply to score more points than the opponent, but it could also be said (without much controversy) that the point is to score as many points as you can while holding the opponent to as few points as you can. Particularly in a league with as few games relative to the amount of teams as college football, margin of victory is a viable differentiator.
  • Strength of opponent is important. A one-point win over a great team is worth more than a 50-point win over a bad team.
  • Date of game is not included. The dates are essentially arbitrary and beyond the control of any team. Also, I have always considered one of college football’s great strengths to be how a game in early September can be just as important as one in late November (and known to be so at the time played).
  • Location of game is not included. I consider location, as well as weather, injuries, etc. to be part of the game that occasionally must be overcome. Even if I felt the location should be included, it would be (in my opinion) impossible to account for the real difference it made on a given day.

Thanks to Ken Massey of masseyratings.com for helping me along.

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