Monday, November 23, 2009

About the Baggaley NCAA FBS Division Football Ranking System

The Baggaley NCAA FBS Division Football Ranking System is a system for ranking the season success of each of the FBS division football programs. Note that there is a technical difference between this and ranking the teams based on which team is BETTER than another team or which team would beat another team if they played each other.

The ranking system is based on the simple premise that if a team beats another team, it should be ranked higher than that team and if a team beats another team by a lot of points, it should be ranked a lot higher than that other team. At the beginning of the season, unlike other ranking systems that release preseason rankings that unfortunately limit the potential of most FBS teams, all teams begin the season with the same ranking. Rankings are then adjusted week to week based only on wins, losses and margin of victory. If you beat a team that is ranked higher than you, they drop in rank and you go up in rank to the point that you are higher ranked than the team you beat. Additional adjustments are applied for the margin of victory, so teams that beat a lower ranked team can still rise based on that margin of victory (although it won't do you any good to score that additional touchdown to beat the other team by 56 instead of 49 - anything over a 20 point victory is considered a blowout and treated equally). Finally, there is a penalty applied to reduce the value of point differential for victories over lower ranked teams. The size of the penalty depends on how much lower ranked the other team is - for example a 21 point victory over a much weaker team might really only as valuable as beating a team that is your equal by a field goal.

That's the basic premise. However, recognizing that this gives an advantage to teams that win late in the season, the order in which the games occur is removed from the calculations by analyzing each team's rankings as if the games had occurred in a variety of different orders that end up weighting the weeks equally, and the rating that is used is an average of each of these possible results. In other words, after week 3, each team's ratings are based on how they would be ranked if week 1 was played first, then week 2, then week 3 AND how they would be ranked if the order of weeks went each of the following orders: 1-3-2, 2-1-3, 2-3-1, 3-1-2, and 3-2-1.

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