The official CHSAA RPI calculations were first used during the Spring 2016 season. They are now in widespread use in
all team sports.
Below are answers to common questions surrounding the RPI system.
What's the RPI formula? And where did it come from?
RPI stands for Ratings Percentage Index. This Wikipedia page is a good starting point for those looking
to become familiar with the formula. In short, it is a way to measure a team's strength relative to other teams,
based largely on the strength of their schedules.
CHSAA first became interested in using an RPI system when searching for a way to standardize all postseason
qualification processes. It was also used by the football committee in 2015 as a component to the seeding
criteria, following a presentation and suggestion from community members. The RPI formula is used by both the
NCAA and NAIA, among other organizations, as part of their postseason system. In August 2015, CHSAA's board of
directors mandated that all committees use RPI for postseason qualification.
What percentages are being used in the formula?
The formula is as follows for all sports:
RPI = (0.3 × WP) + (0.40 × OWP) + (0.3 × OOWP)
Why use RPI instead of another type of rating system?
A major advantage to the RPI is the transparency that comes along with its accuracy. The components of the formula
are known, and its results can be easily replicated.
What data will be used in the RPI formula?
All games played in the regular season shall be counted toward the RPI calculation, with the exception of games
against non-varsity opponents and games against non-member schools. Some sports use district/regional data, as
well, to help with seeding their state tournaments.
Where will be the RPI standings be published?
The official CHSAA RPI standings will be published on CHSAANow.com. It is worth noting that any RPI data published
elsewhere is unofficial and should be viewed with skepticism as it may not be correct.
How are the components of the formula specifically calculated?
-
Winning percentage (WP): Divide the number of wins by the number of total games played.
A tie is worth half a win. If a win in an individual contest gives that contest a winning percentage of
1.00, a tie would give that individual contest a winning percentage of .500 for both teams.
-
Opponents' winning percentage (OWP): Average the winning percentages of a team's
opponents. (Note: This is not calculated via the combined record of the opponents, instead by averaging
each winning percentage of the opponents.) All games involving the team whose RPI is being calculated
are ignored in this process.
-
Opponents' opponents winning percentage (OOWP): The same process as described above,
except calculated for the opponents of a team's opponents. Note that there is an exception for
out-of-state teams, which is addressed below.
How will out-of-state opponents be handled?
Out-of-state opponents from the following states will be counted the same as in-state opponents:
- New Mexico
- Arizona
- Utah
- Wyoming
- Nebraska
- Kansas
In other words, teams will receive the true value of their opponents' opponents winning percentage. This is because
each of the states listed above are neighboring states to Colorado, and each of these states are also MaxPreps
partners. This ensures accurate reporting of data.
All other out-of state opponents will be handled in the following manner: 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 we've run.
Note that it is the responsibility of the Colorado school to ensure that the data from their out-of-state opponent is
correctly listed on MaxPreps.
Note: This does not apply to football. Out-of-state opponents in all states will count the same as an in-state
opponent in football.
How will international opponents be handled?
Due to the difficulty involved with obtaining accurate data on a consistent and timely basis from schools outside the
U.S., international opponents will not count toward the RPI calculation.
Are games against non-varsity teams counted toward the RPI calculation?
No, they are not.
Are games against non-member teams counted toward the RPI calculation? And how are non-member schools
defined?
No, they are not. Non-member schools are schools that are not a member of an NFHS state association. Here in
Colorado, only schools that are part of CHSAA are member schools.
Does my RPI rating go down if I win a game?
No. This is a common misconception. The direct game is not factored into your RPI formula.
For example, if you team plays a team that is 9-0, and you beat them, their record is now 9-1 (for a winning
percentage of .900). However, because the direct game is not included in your team's calculation, they are
factored in as 9-0 for the purposes of your RPI calculation. In other words, their winning percentage for your
calculation remains at 1.000.
This is true even if you play a team twice, or three times. All direct games against that opponent are removed from
the calculation.
Do scrimmages or Foundation Games count toward the RPI?
No, they do not. Note that you should not be putting these games on your official MaxPreps schedule. Instead, put
them on your Team Calendar in MaxPreps. More information is available on this page.
How will cross-classification games be handled?
There are two answers to this question. One pertains to football, and the other pertains to the rest of the sports.
Football will use a modifier to handle these cross-classification games. Other sports will not. The reason for the
difference is football plays a 10-game regular season, which is far-and-away the fewest of any sport. (By
comparison, for example, baseball plays a 19-game regular season, and basketball plays 23.) Thus, there is less
data to work with in football to ensure the accuracy of the result. Using a modifier helps to increase the
accuracy.
The modifier for football will be a 15 percent difference. This number was arrived at when comparing the average RPI
of football teams in different classifications over the past couple of years. On average, there was a 15 percent
difference from a 5A team to a 4A team, from a 4A team to a 3A team, and so on.
Starting in the 2020 season, each football team will be allowed two exceptions for a team playing down. That is to
say, when a 3A team plays a 2A opponent for the first and second times on their schedule, those 2A opponents
will count as a 3A team. Subsequent games against teams from lower classifications will count as their true
classification.
Note that if, for example, a 4A team plays a 2A, an exemption would view the 2A team as a 3A team — not as a 4A team.
This modifier only comes into play when a team wins. Under the modified RPI system which will be used in football,
each game is assigned a value based on that team's classification. Again, there is a 15 percent difference
between them. Those (rounded) values are:
| Class |
Value |
| 6-man |
1.000 |
| 8-man |
1.150 |
| 1A |
1.323 |
| 2A |
1.521 |
| 3A |
1.749 |
| 4A |
2.011 |
| 5A |
2.313 |
So, for example, a 3A team will always have a game value of 1.749, regardless of who they're playing. The value of
the win changes according to their opponent (unless the exemption comes into play). The result gives us a
modified winning percentage. This is the number that will be used throughout the formula, including for their
opponents, and the opponents of their opponents.
Using our example, let's pretend that 3A team (call them Team A) plays another 3A team (Team B), and beats them. They
then play a different 3A team (Team C) and lose to them. The third week, the play a 2A team (Team D), and beat
them. In Week 4, they play yet another 2A team (Team E), and beat them as well. Finally, in Week 5, they play a
third 2A team, and also win that game. Here's what the calculation would for Team A look like:
| Week |
Opponent |
Class |
Result |
Game Value |
Win Value |
Winning Percentage |
| 1 |
Team B |
3A |
W |
1.749 |
1.749 |
1.000 |
| 2 |
Team C |
3A |
L |
1.749 |
0.000 |
0.000 |
| 3 |
Team D |
2A |
W |
1.749 |
1.749 |
1.000 |
| 4 |
Team E |
2A |
W |
1.749 |
1.749 |
1.000 |
| 5 |
Team F |
2A |
W |
1.749 |
1.521 |
0.870 |
Now, Team A in this scenario is 4-1. Their true (unmodified) winning percentage would be 0.800 However, with this
modified system, where their total win value (roughly 6.768) is divided by their total game value (8.745), their
rounded modified winning percentage is 0.774.
Over the course of a season, if Team A were to go 9-1 with wins over all 3A teams the rest of the way, their modified
winning percentage would be 0.887 (as opposed to a true winning percentage of 0.900). It is worth remembering
that this number is 30 percent of the overall formula.
Again, all other sports will not be using the modified system because their regular seasons are much longer.
What happens if two teams are tied in the final RPI standings?
We have created a tiebreaker for this unlikely scenario. It is as follows:
- Head-to-head result between the two teams
- Winning percentage
- Opponents' winning percentage
- Opponents' opponents winning percentage
- Highest-rated win (according to the final RPI standings)
- Next-highest rated win (exhaust all possibilities)
- Coin flip
The only reason for the coin flip is as a last result if all other scenarios happen to be tied.
How should teams be scheduling?
The main thing to remember with the RPI is it takes an entire schedule into account. Do not fret over scheduling one
game. Instead, see the entire schedule as a whole and try to judge if it will be tough or not.
Does the score of the contest matter in the RPI formula?
Only in that it gives a winner and a loser (or results in a tie). There is no factor for score differential in the
RPI formula. A 1-0 win counts the same as 100-1.
What happens if a game is cancelled and can't be rescheduled?
Because the RPI system works off of averages, it won't make a difference in the final formula if a game cannot be
rescheduled. It would not penalize, nor benefit, any team involved in that scenario.
How do schools that drop programs affect the RPI?
If a school drops a program prior to the start their competitive season, no forfeits will be involved. Instead, their
opponents now have open dates in the sports where they were scheduled to play the teams who dropped their
program, and they are free to try and find another game, if possible.
If a school drops a program after their competitive season has started, that team shall forfeit their remaining games
to their opponents.
In this instance, the competitive season is defined as the first day a team plays in a contest.
Where should we be reporting scores?
Continue reporting scores to MaxPreps. The official RPI feed will be calculated off of results entered into that
platform.
How often will the RPI standings be published?
The RPI standings will not publish for the first time until a season hits the midway point.
Once they do, feeds are updated nightly during the regular season.