TWISTR IHSAA SPORTS RATINGS
About the TWISTR IHSAA Sports Ratings
The TWISTR IHSAA Sports Ratings are score-based ratings created for seven IHSAA sports - boys and girls soccer and volleyball in the fall, boys and girls basketball in the winter, and baseball and softball in the spring. The TWISTR ratings are designed specifically for high school sports and are generated to provide an objective view of team strength based on available data.
In season, the TWISTR ratings will generally update on a weekly basis, on Sunday for most weeks. At the start of a new season, the ratings will not update for a few weeks while teams play games and become connected. After a few weeks, the first TWISTR ratings of the season will be released.
TWISTR is an iterative least-squares, score-based ratings system built in the spirit of an Elo model. Team ratings are agnostic to the final result of a game - only the scoring margins are important, as no additional benefit is provided for a win or penalty for a loss. Score tapering and weighting are both included to ensure a team's most competitive games are most influential in the ratings, while screening out instances of clear mismatches and greatly reducing the ratings benefit of running up the score on an opponent.
Each sport includes one page for the All Classes ratings - considered across all classes - as well as individual pages for each enrollment classification. In general, these pages include:
- Rating: Each team is provided a rating, which represents the number of goals, points, runs or sets that team would be favored by against an average opponent. Teams with a positive rating are considered better than average, while teams with a negative rating are considered worse than average. The point spread for a matchup can be found by taking the difference between two teams' ratings.
- Win-Loss-Tie: Each team's record is included - however, the displayed record only includes games between rated teams (and thus, will not include games against most non-IHSAA or out-of-state opponents).
- Strength of Schedule (SoS): A measure of the quality of opponents a team has played. SoS is expressed as the winning percentage we would expect a strong team to have against that team's schedule; a lower SoS value indicates a tougher schedule. The SoS is calculated separately for the All Classes and class-specific ratings, to acknowledge that the makeup of a strong schedule differs from class to class.
- Strength of Record (SoR): A measure of the quality of a team's record over the course of the season. SoR is expressed as the difference between a team's winning percentage and its SoS rating, and teams with a positive SoR have performed better than we would expect a strong team to perform. Like SoS, SoR is calculated separately for All Classes and class-specific ratings. Unlike Rating, the SoR is a direct reflection of your win-loss record and does not consider margin of victory - it can be considered as TWISTR's poll ballot if it had a vote. Note that SoR ratings remove any effect that head-to-head results may have had on an opponent's rating.
- Deviance: The average departure of a team's performance from its rating. Teams with a lower Deviance rating are more consistent game to game, while teams with a higher rating may be more erratic.
For more information about the TWISTR ratings, see the Frequently Asked Questions page.