|Washington’s Rating Percentage Index (RPI) for Basketball|
Basketball RPI Rankings
What is RPI?
RPI, Rating Percentage Index is a statistical system used to comparatively rank teams.
What is the purpose of the RPI?
The purpose of the RPI is to seed teams into the regional and state basketball brackets using this statistical system.
What is the formula of the RPI?
The formula used is as follows: RPI = (40% x WP) + (40% x OWP) + (20% x OOWP)
- WP (Winning Percentage): Divide the number of wins by the number of total games played for your team.
- OWP (Opponents Winning Percentage): Average of the winning percentage of a team’s opponents (Note: this is not calculated via the combined record of the opponents, but rather by averaging the winning percentage of the opponents).
- OOWP (Opponents’ Opponents Winning Percentage: Same process as OWP except the calculation is with the opponents of the team’s opponent. Note: there is an exception for out-of-state opponents – see below.
How will out-of-state opponents be calculated?
Any Washington teams that play out-of-state teams (including Canadian teams) will be expected to monitor those teams' schedules and scores on a weekly basis throughout the season to make sure scores are inputted to MaxPreps. Coaches and athletic directors will be responsible for contacting the out-of-state schools if scores are not being entered.
When calculating out-of-state opponents, their direct winning percentage (for example, .750) will count toward the formula, but each of their opponents will have a .500 winning percentage assigned. Were this not the case, schools would be chasing tens of thousands of opponents of out-of-state opponents over the course of a season, and there is no way to ensure the accuracy of that data.
The .500 figure was selected because it is the average value of opponents' opponents winning percentages across all sports in the data that's been run.
Why use the RPI vs what has been used previously?
The RPI system will be an accurate reflection of all regular and postseason games. Teams will be seeded into the regional bracket based on their RPI ranking versus previous criteria that was based on how teams finished in the District qualifying tournaments.
Will postseason games be taken into consideration?
Yes, all games played through the District qualifying tournaments will be included.
Will teams be re-ranked after the regional round?
Teams will be seeded using the RPI for the regional round only. Teams that qualify for the state bracket will assume the RPI from the regional round. Re-seeding will not be done following the regional round.
What is important to make RPI successful?
Score reporting is essential for an accurate RPI. Scores will be collected in MaxPreps. The WIAA will publish the RPI on its website at wiaa.com. Any other publication sites may not be accurate.
Where should scores be reported?
Scores must be reported on MaxPreps. The official RPI will be based on the scores reported.
Should scores from games played against Australian touring teams be reported?
No, exhibition games against international teams should not be reported.
Should scores from the jamboree be reported?
No, only scores from full games should be reported.
How will the RPI be published?
The RPI will be published on the WIAA website.
How will a team know its ranking?
The rankings will be published beginning the first week in January, 2018. Rankings will be updated daily and published on the WIAA website.
Will it be used for other WIAA sports?
The RPI will be used for basketball only this year. The 2017-18 school year will be a study year for all other team sports, so all full game scores need to be reported into MaxPreps. Although the specific formula may be different, the RPI could expand into other sports as soon as the 2018-19 school year.
Is the RPI for all classifications?
The RPI will be used for all classifications in basketball this year.
What is the impact of cross-classification games?
The formula does not take into account classifications. A team will not be penalized for playing a team in a lower classification nor rewarded for playing against a team in a higher classification (see how the formula is calculated above).
Does the score differential matter in the RPI?
The RPI is based on a win loss formula (see above). Score differential will have no bearing on the RPI.
What if teams have a different amount of games?
The RPI formula works off the averages of three components: winning percentage, opponents' winning percentage and opponents’ opponents winning percentage, so an imbalance of one or two games between teams will have virtually no impact on the ranking system.
Is a team’s RPI based on the opponent’s record at the time the game is played or is the RPI based on the final regular season record of their opponents?
The final RPI calculations used for seeding purposes will be based on the final records of all teams.
How will ties be broken?
A five-step tie-breaking criteria will be utilized to break any ties:
- 1st – RPI score/ranking, taking the value out to as many places as needed (versus only three places)
- 2nd – results of head to head competition (regular season only)
- 3rd – winning percentage (WP)
- 4th – strength of schedule
- 5th – coin flip
How is the strength of schedule (SOS) determined?
SOS is .5*OWP+.25*OOWP
When I try to calculate teams OWP, I get different results than what is shown on th RPI page? How is OWP calculated?
OWP is the average winning percentages of a team's opponents. (Note: This is not calculated via the combined record of the opponents, but rather averaging each winning percentage of the opponents.) It is also important to remember that when calculating OWP (and OOWP), the head-to-head matchup between teams is taken out of the equation. That game already is figured in both teams' WP. The RPI rationale for omitting that is so there isn't a double bonus or a double hit for that specific game to the teams, and you get an accurate reading of how teams rate when they are not playing each other.
Our district gets 4 teams to Regionals. My team earned 4th place in our district tournament, but finished with an RPI at #17 in the final rankings. Does that mean my team is out of the tournament?
District tournaments and allocations still determine the 16 teams that qualify for the Regional games. The RPI is only used to seed those 16 teams into the Regional bracket. There will be instances when a top 16 team according to RPI does not qualify for the Regionals. The next highest ranked team according to RPI will move and take over their seed. For instance, if the #1 - 5 qualifies but #6 does not qualify, the #7 team would move up to become the #6 seed in the Regional bracket. This would be done until all 16 teams are seeded.