The Game Outcome Measure (GOM) is the central metric used by my rating program to determine how much better the winning team is than the losing team in a specific game played. The GOM can be designed to reward offensively-oriented teams (by relying heavily on how many points the winning team scores); another GOM definition might favor defensively-minded teams by relying on how few points a team gives up. Still another might ignore the score altogether and just look at who wins the game.
The choice of the definition of the GOM is the one human element that enters into computer rankings. The computer then applies the GOM criteria uniformly across all games to determine the best team. Naturally, different GOM definitions can result in different final rankings, so it is useful to look at several criteria.
Was the margin of victory (MOV) large or small? Was the winning team playing on the road? Is running up the score on a weak opponent something that should be rewarded? There are many questions worth exploring when designing the GOM. But it is important to keep in mind that the only data that can used (due to the constraints of practicality) are the final score and the location at which the game was played. Any mathematical function that can be defined based on those data can be used.
Due to the large number of games that are played each week, it is difficult to look at any statistics other than the final score. So, based on the score, one can make a few guesses about how a team did offensively and defensively (defined by scoring points and holding the other team from scoring points, respectively.) Of course, the final score doesn’t tell you things like whether points were scored by offense, defense or special teams, or if a team scored a lot of touchdowns or was held to field goals. What the final score does tell you is who won, whether it was a high scoring game or not, and if the home team defended its field or not.
There are also a number of other concerns, such as fairness and offensive bias. Is it a good idea or a bad idea to reward a team for running up the score? On the one hand, it is kind of a dick move, but then again, if a team trots out their second and third strings and is still scoring, it is a fair indication of the winning team’s superiority. Offensive bias is a little bit more difficult. Any GOM definition that includes MOV is inherently going to favor teams that are good because of their offenses. Teams that depend on defense may be dominant, but not score many points, resulting in small margins of victory, which may be reflected in weaker GOMs.
Over the years, I have wrestled with many of these issues (as has the Bowl Championship Series). The BCS has chosen to deal with things by eliminating MOV from consideration. This resulted in some controversy, as many computer raters felt that MOV was a necessary component to produce meaningful results. My personal feeling is that—much like the dual-life nature of a certain feline pet of a prominent developer of quantum theory—the BCS has a point and does not have a point at the exact same time. But much like Schrödinger’s proverbial cat, we will never really know until we move past the BCS era and see if the next system works any better.
The GOM that I currently use in my main ratings is a kind of a hybrid system, designed to reward teams for winning, while providing bonuses for MOV, defensive play, and winning on the road. The GOM is intended to give a measure of how much better the winning team is than the losing team. The GOM is calculated as follows:
Winning 14 MOV bonus 7 (max) Defensive bonus 7 (max) Defensive adjustment -7 (max) Road win bonus 3
There are some considerations on the bonuses. First, the MOV bonus is capped at 14 points to avoid rewarding teams for running up the score on weaker opponents. If the MOV is less than or equal to 14, the winning team is awarded a bonus of half of the MOV. The defensive bonus is given for holding a team at or below 14 points. If this is the case, the winning team is awarded a bonus of (7 – ((losing score) / 2)) Thus, a shutout gives a team the maximum defensive bonus of 7 points. The defensive bonus is also adjusted if the losing team holds the winning team below 14 points. Finally, the “road win” bonus is awarded to a team that wins away from home, but is not awarded if the game is played on a “neutral” field.
All told, the maximum value for the GOM is 31 points. The minimum is 14.5 points. A few examples from the 2013 college football season:
Washington State - 10 Southern Cal - 7 GOM = 14 (winning) 1.5 (MOV) 3.5 (def. bonus for holding USC below 14 points) -2 (def. adjustment for being held below 14 points) 3 (road win) 20 total
USC - 41 Arizona State - 62 GOM = 14 (winning) 7 (MOV) 0 (def. bonus) 0 (def. adjustment) 0 (road win 21 total
Notre Dame - 37 Arizona State - 34 @ Arlington, TX GOM = 14 (winning) 1.5 (MOV) 0 (def. bonus) 0 (def. adjustment) 0 (neutral site win) 15.5 total
San José State - 37 Hawai’i - 27 GOM = 14 (winning) 5 (MOV) 0 (def. bonus) 0 (def. adjustment) 3 (road win) 22 total
Now, onto the rankings for Week 8…
The Fleming System: Week 8 Rankings
(as of October 16th)
|78||San Diego St||3||3||MWC||127.179||128.429|
|83||San José St||3||3||MWC||125.095||124.595|
|86||North Carolina St||3||3||ACC||124.138||126.388|
|96||Texas St-San Marcos||3||3||SunBelt||122.175||121.842|
|100||Middle Tennessee St||3||4||CUSA||121.527||126.17|
|123||New Mexico St||0||6||Ind-FBS||102.191||125.025|