Ratings Percentage Index

Ratings Percentage Index
Name	Ratings Percentage Index
Introduced	1981
Used by	NCAA, NIT, ACC, Big Ten
Purpose	Team ranking for tournament selection and seeding
Domain	College basketball, College football

Ratings Percentage Index

The Ratings Percentage Index is a statistical metric developed to assist NCAA selection committees and sports analysts in comparing team performance for postseason tournament selection, pairing, and seeding. Originating amid efforts by administrators, statisticians, and conference officials to improve objectivity, the metric influenced decisions by the Selection Committee, athletic directors, and broadcasters across conferences such as the SEC and Pac-12. It coexisted with other systems used by organizations including the Associated Press, USBWA, and commercial rating services.

Definition and Purpose

The metric was defined to combine a team’s own winning percentage with the strength of opponents and the strength of opponents’ opponents, providing a single-number proxy for team quality used by entities such as the NCAA Division I Men's Basketball Committee, conference commissioners, and media outlets like ESPN. The primary purpose was to offer an objective complement to subjective polls such as the AP Poll and Coaches Poll, aiding in decisions by the Selection Committee and by tournament organizers in assigning at-large bids and seeding for events like the NIT and conference tournaments.

Calculation Methodology

The traditional formula weights three components: a team’s own winning percentage, opponents’ winning percentage, and opponents’ opponents’ winning percentage. The computation requires game results tracked by bodies such as the NCAA and conferences including the Big East Conference and uses datasets maintained by agencies like Ken Pomeroy-style databases and media services exemplified by Sports Illustrated archives. Practically, the calculation aggregates win–loss records compiled by athletic departments, incorporates adjustments for neutral-site and home/away games sometimes used by statistical services such as ESPN and CBS Sports, and produces a normalized percentage for comparison across teams from leagues like the Atlantic Coast Conference and Big Ten Conference.

Historical Development

The metric emerged in the early 1980s amid debates involving figures from the NCAA, conference commissioners, and media organizations. Over decades it was discussed alongside metrics created by statisticians affiliated with institutions such as Ken Pomeroy’s analytics, models used by Jeff Sagarin at USA Today, and rating systems promoted by broadcasters like CBS Sports and ESPN. Revisions and critiques occurred during high-profile selection controversies involving programs from the University of Kentucky, Duke University, and University of North Carolina, and in seasons where at-large selections prompted scrutiny from outlets including the New York Times and Sports Illustrated.

Use in Sports Selection and Seeding

Selection committees for the NCAA Division I Men's Basketball Tournament and conference tournaments have used the index alongside the NET and other metrics to structure at-large bids and seed lines. Athletic directors, commissioners from conferences such as the Big 12 Conference and American Athletic Conference, and television partners at networks like ABC have cited statistical metrics when defending bracket choices. The index historically informed metrics databases used by historians at institutions such as the College Basketball Hall of Fame and by analysts at outlets like Bleacher Report when constructing comparative performance tables.

Criticisms and Limitations

Critiques arose from statisticians, coaches, and journalists at organizations like the Associated Press and Sports Illustrated over issues including sensitivity to scheduling imbalances among conferences such as the SEC and Pac-12 Conference, inadequate adjustment for margin of victory compared with systems developed by Ken Pomeroy and Jeff Sagarin, and potential biases when teams play unequal numbers of nonconference games. Analysts affiliated with universities including Duke University and University of Michigan noted that reliance on simple win–loss aggregates can misrepresent team quality compared to models incorporating play-by-play data used by services like Synergy Sports Technology and advanced analytics groups tied to FiveThirtyEight.

Variants and International Equivalents

Variants and analogous indices exist in other sports governance systems and international competitions, such as rating adaptations used by UEFA for club coefficients, performance indices employed by the FIBA in continental qualification, and proprietary rankings from companies like Sportradar. National governing bodies in countries with prominent leagues—examples include the English Football League and federations in Spain and Italy—use bespoke strength-of-schedule and coefficient systems that serve similar selection and seeding functions in competitions like continental cups and domestic playoffs.

Category:College basketball statistics