Behind the Numbers

Fan Formula wants to change the way fans think about the Top 25 college football and basketball rankings. Designed by professional business analyst, John Schroeder, Fan Formula’s methodology dissects, digests and resolves the motives, principles and biases that impact how people and computers determine which teams are #1.

Generating Accurate Numbers with The Vegas Spread Index

Fan Formula’s numbers were calculated based on three fundamental beliefs:

• To determine accurate rankings, a defensible estimate of how strong each team is compared to all others must be established - we call ours the Vegas Spread Index (VSI).
• To make the VSI most valuable it must be represented in terms fans can most easily understand. Therefore, the VSI represents a team’s strength as how many points a team is better or worse than average, e.g. 7 points better, 3 points worse, etc.
• The primary input for calculating the strength of a team is the weekly Las Vegas lines which reflect the "collective wisdom” of all sports bettors.

In theory, a team’s VSI should be simple and straight forward to compute with the help of the transitive property of mathematics. If Florida is 10 points better than Tennessee and Tennessee is 7 points better than Kentucky, then Florida is 17 points better than Kentucky. Play this computation out game after games week after week and, voila!, you have computed the relative strength of every team.

In practice however, examining every game, outcome, and spread from the BCS era reveals some surprising complexities that must be resolved to maintain accurate numbers. These variations include:

• Adjusting for home field advantage - which is nowhere near as straightforward as it sounds.
• Balancing if changes in the point spread are more a reflection of the strength of the favorite team or the weakness of the underdog.
• Maintaining the integrity of a quantitative formula while striving to reflect a myriad of external and human factors including injuries, rivalry games, coaching changes, rematches, postponements, etc.

Building the Rankings

Once there is a defensible measure of team strength, many of the other factors quickly fall into place.

Win_Points:To calculate the value of a win, simply reward a team based on the VSI of the team defeated. If Oklahoma defeats a Texas team with a VSI of 19 on a neutral field, Oklahoma would receive 19.0 Win_Points.

To adjust for home field advantage, Oklahoma would receive ~17.5 Win_Points for defeating Texas at home, 19.0 on a neutral field, or ~20.5 Win_Points for defeating the Longhorns in Austin.

Fan Formula rewards zero credit for beating below average teams or Div 1-AA teams.

Loss_Points: To calculate the penalty for a loss, the VSI is used in reverse. Why reverse? Because teams should be penalized more for losing to bad teams than for losing to good teams.

The Quality Win-Loss Matrix is calculated by subtracting loss points from win points to develop a single measure of a team’s season based purely on who they beat and who they lost to (while ignoring margin of victory).

Road Warrior Ranking: To calculate a team’s road warrior ranking, simply sum up their win points from all games played on an opponent’s home field.

True Style Points: To calculate a team’s style points, compare the final score to an opponent’s VSI. If Oklahoma beats a Texas team with a VSI of 19.0 by 1 point, Oklahoma receives 20 style points, if they lose by one point they receive 18 style points.

True Style Points represents how a team looked in each game (e.g. 20 points better than an average team in the example above) and can be combined across the season to show a team’s average performance.

Hot Streak Thermometer: The Hot Streak Thermometer is perhaps the most subjective of any of the six main ranking systems employed at Fan Formula. After many permutations the Hot Streak Thermometer landed on a formula including:

• A team’s performance over the past four games
• Weighted 40%, 30%, 20%, 10% so the most recent games count most heavily
• With performance based on both the strength of a team’s opponents and margin of victory

The Hot Streak Thermometer rating is then scaled to be readily recognizable as degrees Fahrenheit with a baseline of 70°F for average teams, cold teams dipping down into the 40s, and hot teams in the upper 90s.

Undefeated SoS: To rank only the undefeated teams based on strength of schedule, Fan Formula sums up each undefeated team’s win points (after all they have no loss points – they’re undefeated).