How are the college football rankings determined?

The Four Variables Explained

The Associated Press (AP) and USA Today/ESPN Coaches Poll Ratings
Two subjective polls, The Associated Press ranking and USA Today/ESPN Coaches Poll make up the first variable. Both of these polls have been around for many years and have an established track record. Both of these are personal choice polls. They are called this because members of both groups cast their votes based on what they think about a team's performance. Both groups also know a whole lot about football. A national board of sports writers and broadcasters participate in the AP poll, and a select group of football coaches determines the USA Today ratings. The BCS incorporates their input by averaging team rankings from these polls. For example, a team ranked No. 3 in one poll and No. 5 in the other would get four points in this category.

Computer ranking
There are eight computer-generated rankings that make up this variable. The rankings are actually the output of computer programs that crunch weekly game statistics. Most of these programs were designed by people with backgrounds in math or statistics. Their formulas factor in an eclectic mix of variables, from who won to where a game was played.

To get a team's point total, the lowest ranking is dropped, and the remaining seven are averaged to produce the team's score. This prevents any one computer's results from ruining a team's chances at No. 1 or 2. For example, if a team is ranked 1, 1, 1, 1, 4, 2, 2, 1, the fourth place finish will be dropped. A team's final computer ranking would then be

( 1 + 1 + 1 + 1 + 2 + 2 + 1 ) / 7 = 9 / 7 = 1.29

rather than what they would have scored with all eight included

( 1 + 1 + 1 + 1 + 2 + 2 + 1 + 4) / 8= 13 / 8 = 1.63

Some of the teams at the top of the BCS ranking can be separated by tenths of points, so a difference of 0.34 points is no small matter!

Computer Ranking Run by Important variable
Billingsley Report Richard Billingsley, businessman Strength of opponent, final score, won-lost records of teams (before and after the game)
Dunkel Index John Duck, statistician Strength of schedule, won-lost record, the upset factor
Massey Ratings Kenneth Massey, mathematics graduate student Overall team rating, offense and defense specific ratings, strength of schedule, home-field advantage
New York Times (NYT) Marjorie Connelly, editor of NYT surveying department Margin of victory, strength of schedule, recent performance
Rothman David Rothman, retired mathematician Number of wins, margin of victory, quality of opponent
Sagarin's USA Today Jeff Sagarin, mathematician and MBA Margin of victory, strength of schedule, location of game
Scripps-Howard Herman Matthews, mathematics and computer science professor Game score, penalty for running up score, strength of schedule
Seattle Times Jeff Anderson, political science graduate student
and Chris Hester, sportswriter and broadcaster
Quality of opponent, strength of schedule