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NCAA.com | November 26, 2018

The NET, explained: NCAA adopts new college basketball ranking to replace RPI

This story was originally published Aug. 22 and has been updated.

The NCAA has developed a new ranking system to replace the RPI as the primary sorting tool for evaluating teams during the Division I men’s basketball season. The new ranking system was approved in late July after months of consultation with the Division I Men’s Basketball Committee, the National Association of Basketball Coaches, top basketball analytics experts and Google Cloud Professional Services.

The NCAA Evaluation Tool, which will be known as the NET, relies on game results, strength of schedule, game location, scoring margin, net offensive and defensive efficiency, and the quality of wins and losses. To make sense of team performance data, late-season games (including from the NCAA tournament) were used as test sets to develop a ranking model leveraging machine learning techniques. The model, which used team performance data to predict the outcome of games in test sets, was optimized until it was as accurate as possible. The resulting model is the one that will be used as the NET going forward.

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The NET was built to create a ranking system that was as accurate as possible while also evaluating team performance fairly. To ensure fairness, certain types of data were omitted from the model. Of key importance, game date and order were omitted to give equal importance to both early and late-season games. In addition, a cap of 10 points was applied to the winning margin to prevent rankings from encouraging unsportsmanlike play, such as needlessly running up the score in a game where the outcome was certain.

“What has been developed is a contemporary method of looking at teams analytically, using results-based and predictive metrics that will assist the Men’s Basketball Committee as it reviews games throughout the season,” said Dan Gavitt, senior vice president of basketball for the NCAA. “While no perfect rankings exist, using the results of past tournaments will help ensure that the rankings are built on an objective source of truth.”

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This marks the second consecutive year the committee has made a significant change. Before last season, a quadrant system was adopted to place greater emphasis on success in games played away from home on the team sheets, which offer a snapshot of each team’s schedule and results. The existing quadrant system still will be used on team sheets, with the NET replacing the Rating Percentage Index to sort games based on the opponent’s ranking:

Quadrant 1: Home 1-30, Neutral 1-50, Away 1-75
Quadrant 2: Home 31-75, Neutral 51-100, Away 76-135
Quadrant 3: Home 76-160, Neutral 101-200, Away 135-240
Quadrant 4: Home 161-353, Neutral 201-353, Away 241-353

While the quadrant system was widely deemed an improvement to the selection process, the NET is another significant step in addressing the recommendations the NCAA received from the NABC’s ad hoc committee, whose purpose was to make recommendations regarding the selection, seeding and bracketing of teams.

Another change made last year to the team sheets was the inclusion of other metrics. These include the Kevin Pauga Index and ESPN’s results-oriented metric, the Strength of Record. The team sheets also included three predictive metrics: those managed by renowned basketball analytics experts Ken Pomeroy and Jeff Sagarin, as well as ESPN’s Basketball Power Index.

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“The NCAA Men’s Basketball Committee has had helpful metrics it has used over the years, and will continue to use the team sheets, but those will now be sorted by the NCAA Evaluation Tool,” Gavitt said. “As has always been the case, the committee won’t solely focus on metrics to select at-large teams and seed the field. There will always be a subjective element to the tournament selection process, too.”

The RPI was first used in 1981 and was developed by the NCAA to provide supplemental data to the Men’s Basketball Committee, which is responsible for selecting at-large teams and seeding and bracketing teams in the NCAA Division I Men’s Basketball Championship each year. The RPI still will be used by other Division I sports committees, including the Women’s Basketball Committee for the 2018-19 season.