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Wednesday, January 10, 2007

Elite Selection Playoff Explanation

As many of you know, my friend Vinnie and I came up with our own version of the BCS. Each year we will release it beginning the sixth week of the season and going through the final regular season games (including conference championships). For extra flare we even gave it a name: the Elite Selection Playoff, or ESP.

Our goal was to understand how college football computer rankings and the BCS system work by creating our own version. Specifically, we wanted to develop a computer ranking to model the performance of college football teams using our own set of criteria. We examined the multiple computer rankings that are used in the BCS system but ultimately decided to start from scratch. We wanted the criteria to be both quantifiable and objective. We also wanted to keep the model fairly simplistic.

After some debate we narrowed it down to four things: quality wins and losses, strength of schedule, margin of victory, and adjusted win percentage. Quality wins and losses are wins against a ranked opponent and close losses (quantified by a specific scoring differential value) to a ranked opponent. A ranked opponent is a team in the top 25 of the computer ranking. This ranking changes as the season progresses. That is to say, a team only receives credit for wins and close losses against a team that is currently ranked in the top 25 of the computer ranking. We believe this to be a unique feature of our computer ranking.

Strength of schedule is as simple as it sounds and is probably calculated using a very similar method to the other computer rankings used by the BCS with one exception. A slight debit is given to the strength of schedule for teams who schedule opponents outside of Division IA. Credit for margin of victory is given based on the scoring differential, i.e. the difference between points scored and points allowed. Finally, the win percentage of each team is adjusted to give slightly more credit for road wins and a small debit for home losses.

There are three equally weighted parts to the final, ESP ranking: the AP Poll, Coachs' Poll, and AV computer ranking. We selected the AP and the Coachs' Poll because we tend to believe (perhaps incorrectly) that those who vote in these two polls are more educated about college football than the Harris Poll. The AV ranking is Vinnie and my computer ranking based on multiple part formulas calculated using a weighted average of the criteria discussed above.

Four things will be presented for the ESP. First, the final ESP ranking will be shown for the top 25 teams. Second is the ESP bracket, an eight team playoff bracket using the top eight ESP ranked teams. The third is the AV ranking for the top 25 teams. Finally, the top ten teams in each of the four AV ranking categories (strength of schedule, quality wins/losses, adjusted win %, and margin of victory) will be shown.

The ESP ranking file used to be posted on the internet but for various reasons (including keeping the formulas confidential) I decided to take it down. Updates will now be shown in the form of blog posts.

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