As we are getting closer to selection Sunday, rating college basketball teams is mainly about identifying NCAA tournament teams. Ultimately the tournament itself decides who becomes the Champions, but the question every year is what teams deserves to be there?
There are always controversies involved in this process especially with the seeding process and also when a bubble team did not quite make it in for whatever reasons the NCAA tournament committee gives.
Due to its simplicity, the NCAA tournament committee uses Rating Percentage Index (RPI) as the biggest decision aid in deciding which teams to invite to "March Madness" and where to seed them even though it does not account for actual scores of games. At times this process can be just as controversial as the current computer matrix being used to decide which two teams will compete for the NCAA Division I College football’s BCS title.
Besides the RPI, other power rankings exist; the Sagarin, Massey and Ken Pomeroy’s. All of these methods including the RPI are based upon the outcomes of games, locations and the quality of their opponents. Each one puts these components together in slightly different ways and will arrive at slightly different results.
In recent years the ESPN analytics department created a method known as College Basketball Power Index or BPI for short. They believe that this method is a little more refined than any other existing power ranking. This method has a number of small details involved in their methodology to make it a more accurate reflection for an NCAA tournament team but many readers will not be interested so I will stay away from the technical aspects of it and stick with the simplicity of their method.
On top of the technical details ESPN’s analytics department decided to incorporate a little more information than other power ranking systems being used. In particular, they added a way of accounting for missing players. If a team or its opponent is missing one of its most important players (determined by minutes per game) for a contest, that game is less important for ranking the teams compared to games in which both teams are at full strength.
analytics strongly believes that the College Basketball Power Index (BPI) gives them a tool for rating teams that is more useful than existing tools. It explains a team's wins and losses in a more detailed context and seemingly predicts future results as well as other tools, if not better. It also incorporates information about injuries and missed games that should be relevant for weighting the résumés of bubble teams on Selection Sunday. He is confident that it will enhance coverage of college basketball for years to come.
In my opinion I like the BPI method, but please do not confuse that with me believing that this is a strong tool to predict the winner of the NCAA title. I do believe strongly that if teams were missing key players in their lineups during a loss then it should be factored in with all rating systems for regular and post season action. Many including myself believe the current RPI method lacks theoretical justification from a statistical standpoint. Other ranking systems which include the margin of victory of games played or other statistics in addition to the win/loss results have been shown to be a better predictor of the outcomes of future games. However, because the margin of victory has been manipulated in the past by teams or individuals in the context of gambling, the RPI lessens the chances of such manipulation.
The downside to the RPI method is with so much emphasis placed on Strength of Schedule (SOS) this strongly favors and gives an unfair advantage to teams from major conferences. Very rarely do you have multiple teams coming out of the same mid-major conference.
Provided by Espn.comSystem comparison
How is the College Basketball Power Index by the ESPN Stats & Information group different than RPI or other advanced rating systems like Kenpom.com and Sagarin? Here is how the included elements compare to other systems.
By capturing blowouts, but not overweighting them, BPI credits the ability of good teams to easily beat poor teams without providing incentive to win by 30 when 20 is a safe margin. By capturing both blowouts and close games in this way, BPI summarizes a team's résumé for the NCAA tournament well.
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