The NCAA Division I Women’s Basketball Committee announced that beginning with the upcoming 2020-21 season, the NCAA Evaluation Tool will replace the Ratings Percentage Index as the contemporary sorting tool used to measure a team’s quality and help evaluate team resumes for selection and seeding in the Division I Women’s Basketball Championship.
“It’s an exciting time for the game as we look to the future,” said Nina King, senior deputy athletics director and chief of staff at Duke, who will be chair of the Division I Women’s Basketball Committee in the 2020-21 academic year. “We felt after much analysis that the women’s basketball NET, which will be determined by who you played, where you played, how efficiently you played and the result of the game, is a more accurate tool and should be used by the committee going forward.”
The use of the women’s basketball NET was approved after a lengthy evaluation process, which included a comprehensive assessment of the strengths and weaknesses of the men’s basketball NET that has been used by the Division I Men’s Basketball Committee as a sorting tool since the 2018-19 season. After an analysis of women’s basketball statistical data over a 10-year period by a team from Google Cloud Professional Services, the Division I Women’s Basketball Committee concluded the NET algorithm built exclusively for women’s basketball was an optimal ranking tool and should be used beginning with the coming season.
WHAT IS THE NET?: All your frequently asked questions answered here
The women’s basketball NET includes adjusted net efficiency and team value index. Adjusted net efficiency is a measure of a team’s overall performance during the regular season, determined by the difference between offensive efficiency (points per possession) and defensive efficiency (opponents’ points per possession). Adjusted net efficiency also accounts for strength of opponents (as measured by their adjusted net efficiency) and location (home/away/neutral) of the games (against Division I opponents only). Team value index is the results-oriented component of the NET, ranking more highly those teams that played and beat other good teams, factoring in opponent, location of the game and winner.
In both adjusted net efficiency and team value index, the same performance against the same opponent will be valued more on the road than at a neutral site, and more at a neutral site than at home.
“I want to emphasize that the NET, like the RPI, will be one of many criteria used by the committee in the selection of the 32 at-large teams and seeding of the 64 teams which make up the bracket for the Division I Women’s Basketball Championship,” King said. “What we found during our comparison analysis was that the NET does a more precise job measuring opponent quality given performance than RPI has been able to provide. Doing well on the court and beating good teams continues to be imperative.”
The women’s basketball NET algorithm differs in structure from that developed for men’s basketball.
“While the men’s and women’s basketball NET share high-level goals and individual components, the NET algorithm used in each is different,” said Lynn Holzman, NCAA vice president of women’s basketball. “The machine learning model developed for each sport utilizes only that sport’s data. The women’s model uses only women’s game data, while the men’s model only uses men’s game data. The weights for each are trained using the historical data from the respective sports with each accurately measuring the quality of a team.”
After almost a year of analysis, the Division I Women’s Basketball Committee decided the time was right for full implementation of NET for 2020-21, with RPI no longer being used. RPI was created in 1981 to provide supplemental data for the Division I Men’s Basketball Committee in its evaluation of teams for at-large selection and seeding of the championship bracket. The Division I Women's Basketball Committee began using RPI in 1984.
“The committee determined there was no perfect time to implement the use of NET and that scheduling, whether with RPI or the NET, should be viewed similarly,” King said. “Both metrics are used primarily as sorting tools with the emphasis still being placed on who you played, where you played and the result of the game.”
The women’s basketball NET rankings will be provided publicly on a daily basis on ncaa.com and ncaa.org starting in early December and continuing throughout the upcoming 2020-21 season.
“The WBCA (Women’s Basketball Coaches Association) applauds the continuing efforts of the NCAA Division I Women’s Basketball Committee to advance the NCAA tournament, one of the greatest women’s sports assets in the world,” said WBCA Executive Director Danielle M. Donehew. “The NET is a new, modern metric that will serve as just one of the many tools used by the committee to determine at-large selections and seed the entire field of 64 teams. We appreciate the opportunity, provided by the NCAA, to allow member representatives of our coaches to provide feedback and discuss the rollout. All agree that communication and education will be vital during this transition. The WBCA will provide member coaches with as much information as possible to help them understand and master this new tool.”
Additionally, the Division I Men’s Basketball Committee will conduct their spring meeting via videoconference on May 7. Part of their agenda will be to review a possible tweak to the NET model that the Men’s Basketball Committee and Google have been assessing and evaluating over the past two seasons.