Division I women's basketball is moving to the NCAA Evaluation Tool (NET) starting with the 2020-21 NCAA tournament and will no longer use the RPI. Men's basketball made this move before the 2018-19 season.
The NET, like the RPI, is a sorting tool for NCAA tournament selection of 32 at-large teams and the seeding of all 64 teams on the bracket. The NET is determined by whom a team played, where it played, how efficiently it played and the game result.
The NET is not the sole factor for NCAA tournament selection, of course, just as the RPI wasn't. These other criteria remain: availability of talent (injuries, for example), bad losses, common opponents, being competitive in losses, overall record, conference record, non-conference record, early-in-season vs. late-in-season competition, head-to-head results, regional rankings, strength of schedule, strength of conference and significant wins. There is also some subjective evaluation from personal observation that is included in committee discussions.
As for why the decision was made now, the NCAA women's selection committee said the NET is a more accurate and contemporary tool than the RPI, and after studying how it was implemented on the men's side, it was decided to do the same for women.
The NCAA women's tournament began in 1982. The RPI -- Rating Percentage Index -- was first utilized for the women's tournament in 1984. It measured: D-I winning percentage, opponents' winning percentage and opponents' opponent winning percentage.
While the NET algorithm is fundamentally very similar to that used for the men, it was developed by studying women's basketball data exclusively over the past 10 years. The NET includes two factors: Adjusted Net Efficiency and Team Value Index. Here are what those mean:
*-Adjusted Net Efficiency: measures the difference between offensive efficiency (points per possession) and defensive efficiency (opponents' points per possession). It 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: This ranks 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.
The NCAA will post NET rankings during the season on its website, just as it did for the RPI, starting each year in early December.
Lynn Holzman, the NCAA's vice president of women's basketball, told ESPN's Holly Rowe the move to NET is all about using the best information available to measure a team's qualifications for postseason play.
However, the NET algorithm/formula isn't released publicly. The NCAA said that's because Adjusted Net Efficiency and Team Value Index "are calculated using machine learning models implemented over many of lines of code, with the calculations adjusting with new results each day in such a way that there is no static 'formula' for them." The NET model will be adjusted annually to include the most recent season of data.
Teams were not given more advance notice that the NET would be implemented next season, the NCAA said, because nothing should change about teams' scheduling philosophy with the move to the NET.
"NET does a more precise job measuring opponent quality given performance than RPI does," the NCAA said in a statement. "So teams' aim should be to play their best and not worry about ways to schedule to 'game' the system. Doing well on the court and beating good teams will be rewarded."