About the GBE Computer Ratings
Frequently Asked Questions- What are the GBE Ratings?
- How are the ratings computed?
- When are the ratings updated?
- Why wait until October to publish the ratings?
- What about games against Division 1-AA teams?
- Can I link to or reproduce the GBE Ratings?
What are the GBE Ratings?
The GBE Ratings are based on a fan's view of how college football teams should be rated. The ratings were created in 2003, in the midst of the great debate over who should play in the BCS National Championship game. Arguments for each team (LSU, USC, Oklahoma) were made, but no argument clearly trumped any other.
The GBE Ratings were created to compare teams based on two things:
- How strong was the team's schedule?
- How did the team fare against that schedule?
Without a playoff system, there is no way to say that any team is definitively better than any other. By comparing schedule strengths and the results of the games played against that schedule, it is made clear which teams are stronger.
How are the ratings computed?
The formula for computing the GBE Ratings is x/y, defined as follows:
where x=w/(w+l) (win score, computed as follows:)
- w=(home wins*.95)+(road wins*1.05)+(neutral wins*1)
- l=(home losses*1.05)+(road losses*.95)+(neutral losses*1)
- home wins count as .95
- road wins count as 1.05
- home losses count as 1.05
- road losses count as .95
- neutral wins count as 1
- neutral losses count as 1
This takes into account that on average, in a match between two equal teams, the home team tends to win 5-10% more often, based on observations over the years.
and where y=(2/o)+(1/q) (strength of schedule, computed as follows:)
- o=opponents' win %
- q=opponents' opponents' win %
This gives more weight to the strength of the teams you have played, but tempers it with the records of the teams that they have played. This way a team cannot benefit from beating up on teams that have fattened their records by beating up 0-11 teams all year long as much as they can by winning against teams that have played teams with better records.
These opponents' wins are not weighted for home/away conditions, which may cause a shift in the ratings if ever "corrected for". As of right now, these percentages are straight-up wins versus losses.
The final ratings are multiplied by 10000 to give the numbers a "substantial look" - i.e. a team won't have a rating of .2345, they will have a rating of 2345.
When are the ratings updated?
After the last game of the week is played. Until 2006, the last game of the week was usually a game played on the west coast or in Hawaii. In these cases, the GBE Ratings will be updated sometime Sunday morning.
Starting in 2006, ESPN has been moving one or more games per week to Sunday evening. In weeks with a Sunday game, the GBE Ratings will be updated either late Sunday evening after the game or early Monday morning.
Why wait until October to publish the ratings?
The GBE Ratings are not posted until the games of the first weekend in October because of large fluctuations and anomalies in the ratings that appear after only a few games have been played. By the first weekend in October, the ratings are still very fluid, but enough data have been collected to be able to properly compare the teams.
Additionally, by this point in the season, it is rare (but still possible) for a team to have no rating. To have no rating, a team must have a) played no games, b) opponents who have won no games, or c) opponents who have played only against opponents who have won no games. Each of these scenarios results in division by zero somewhere in the formula.
What about games against Division 1-AA teams?
For the purposes of these ratings, those games do not count towards a team's strength of schedule. As these ratings only cover NCAA Division 1-A teams, games played outside of this division are recorded only as wins and losses - no strength of schedule points are added or subtracted at present.
Can I link to or reproduce the GBE Ratings?
Feel free to reproduce or link to these ratings all you wish. All that I ask is that proper credit be given to this website when doing so.