NCAA Evaluation Tool to Replace Ratings Percentage Index

Starting next season, the NCAA Evaluation Tool will replace the Ratings Percentage Index as one of the primary sorting tools used to measure a team’s quality and help determine selection and seeding in the Division I Women’s Basketball Championship.

The NET has been used in Division I men’s basketball since the 2018-19 season, and the Division I Women’s Basketball Committee approved the tool’s use after evaluating its viability in the men’s game and after considering an analysis of women’s basketball statistical data over a 10-year period which suggested that the NET algorithm was a better ranking tool.

“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.”

According to the NCAA, the women’s basketball NET includes adjusted net efficiency and team value index. Adjusted net efficiency measures a team’s overall regular season performance by calculating the difference between offensive (points per possession) and defensive efficiency (points allowed per possession). Additionally, it helps to account for the strength of different opponents and location of games. Team value index also factors in opponent strength and location in addition to game results in order to increase the ranking of teams that played and beat other good teams.

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• Your Day in Women’s Basketball, March 23: Highlights from the first round of the NCAA Tournament
• Your Day in Women’s Basketball, March 16: Tournament bracket released

The RPI, which has been used in Division I women’s basketball since 1984, provided a ranking of each institution based on their Division I winning percentage and strength of schedule. Compared to the NET, the RPI only consisted of Division I winning percentage, opponent winning percentage and opponents’ opponent winning percentage. Thus, the NET is technically a more accurate tool for measuring the quality of a team.

“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,” said Nina King, Duke’s senior deputy athletics director, who will be chair of the Division I Women’s Basketball Committee for the 2020-21 academic year. “Doing well on the court and beating good teams continues to be imperative.”

The South Carolina Gamecocks earned the No. 1 RPI ranking last season after finishing with a 32-1 overall record (16-0 in the SEC) and ended the year on a 26-game winning streak after winning their fifth SEC Tournament championship in six years.

Going forward, the NET will be used along with traditional criteria like overall record, strength of conference, head-to-head outcomes and more to select the 32 at-large teams and seed the 64 teams which make up the bracket for the NCAA Division I Women’s Basketball Championship.

Like past RPI rankings, 2020-2021 women’s basketball NET rankings will be provided publicly on a daily basis on ncaa.com and ncaa.org starting in early December.

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