INTRODUCTION TO THE MICHIGAN POWER RATING (MPR)
What is MPR?
Michigan Power Rating, or MPR, is a computer rating formula similar to the popular RPI rating. MPR provides a way to measure a team’s strength relative to other teams, based on games played against other MHSAA tournament teams, largely on the strength of a team's opponents' schedules. MPR is purely objective using only the game results listed on MHSAA.com – there is no subjective human element.
What is the basic MPR formula?
MPR is calculated using wins, losses and ties for games played between teams entered into the MHSAA tournament. The final MPR number is 25% of the team's winning percentage, plus 50% of its opponent's winning percentage, plus 25% of its opponent's opponent's winning percentage.
MPR = (.25 x W%) + (.50 x OW%) + (.25 x OOW%)
What game data is included in the formula? What game data is not?
MPR looks only at results between opponents entered into the MHSAA postseason tournament. Wins, losses and ties in multi-team shortened game tournaments (lacrosse, soccer) also count. Forfeits also are counted as wins and losses.
MPR does not use the specific scores of a game or the margin of victory in a game. The location of a game is not included in the MPR formula, and the formula weighs games at the beginning of the season the same as scores at the end of the season. Scrimmages are not included.
Why use the MPR formula?
Different rating systems have been used in the past or have been recommended to the MHSAA. We wanted to have a rating system where the data was controlled and stored in house, and could be used for any sport featuring head-to-head competitions. With its own rating system the MHSAA can control the different components of the formula, thus keeping the tenets of scholastic competition at the forefront (for example, by not including margin of victory in the formula). Finally, by listing all scores and team schedules online, as well as showing the MPR calculator on each team schedule page, the ratings are transparent and can be replicated easily.
How will MPR be used?
Initially, MPR will be used in Boys Lacrosse (spring 2019) as one of the tools for seeding its tournament. Other sports eventually may use MPR, potentially as the lone criteria for seeding teams (basketball and soccer will start in 2019-20). In addition, some sports may add qualification requirements in order for a team to be seeded (like a team must have X number of submitted results in order to be seeded). In the meantime, the MPR data simply provides a fun way to compare teams and schedules from across the state.
What are the detailed components of the MPR formula?
You need three numbers to calculate your MPR: winning percentage (W%), opponent’s winning percentage (OW%) and opponent’s opponent’s winning percentage (OOW%).
How do you calculate winning percentage (W%)?
Divide the number of wins by the number of total games played. A tie is worth half a win. For MPR purposes, find the winning percentage against all teams that will play in the MHSAA tournament (MPR W%). Games played against out-of-state teams, varsity “B” teams, junior varsity teams, non-school club teams, and any other non-MHSAA tournament participants should not be included when calculating winning percentage. W% should be an easy number to calculate.
How do you calculate opponent’s winning percentage (OW%)?
Average the winning percentages of a team's opponents. When calculating the winning percentage of a specific opponent, use the opponents "Adjusted Winning Percentage" (ADJ W%). Adjusted winning percentage eliminates all games the team played against that opponent (as well as its games against non-MHSAA opponents). For instance, if the team beat an opponent with an overall record of 4-1, use a record of 4-0 (1.000) for that opponent. If the team lost to that opponent, use a record of 3-1 (.750). Find the ADJ W% for all of opponents, and then take the average. If a team plays an opponent twice, that opponent’s ADJ W% will be counted twice. OW% is not calculated via the combined record of the opponents; instead, take the average of all opponents' winning percentages. This is a tougher number to manually calculate, but it can be done.
How do you calculate an opponent’s opponent’s winning percentage (OOW%)?
Use the same process as described above, except calculated for the opponents of a team's opponents. This number is much harder to manually calculate, so the OW% for every team is listed on the MPR page of the MHSAA website. Again, simply take the average of all opponents' OW%.
How often is MPR calculated?
MPR is calculated about every five minutes. Enter a score and a few minutes later the team's MPR and the MPR of all the team's opponents will update.
How much will my MPR change throughout the season?
You will see wild MPR swings during the beginning of the season, but after about 10 games played your MPR will start to level out. At 20 games played you will see very little movement with each additional game played.
My score is missing. How can it be added?
This is a crowd-sourced system. Any registered user of MHSAA.com can add a missing score. ADs, coaches, parents, students and fans all can login and enter a score for any game.
What are some common errors when calculating MPR?
When calculating your team’s winning percentage, include only games against MHSAA-tournament teams. When calculating your opponent’s winning percentage, don’t include the games your opponent played against you. When calculating ties, count the game as a half-win and half-loss.
What happens if a game is cancelled and is not rescheduled?
Because the MPR system works off of averages, it will not make a difference in the final MPR if a game cannot be rescheduled. It would not penalize, nor benefit, any team involved in that scenario.
USING THE WEBSITE
Where can I find game scores?
A list of statewide scores for all sports can be found in the MHSAA Score Center. To find a schedule for any team click on “Schools & Schedules” in the top navigation bar, search for the school, then once on the school page click the sport. You also can see a list of all schools (with links to schedules) on the statewide MPR list.
How should I use the statewide list of teams and MPR?
This page is a statewide listing of all Michigan Power Ratings (MPR) for teams entered into the MHSAA postseason tournament. The data updates every five minutes. Click on the column headings to sort the data. You also can use the drop-down menu to show teams in one Division, or type a Region number in the box to filter teams for that Region. You also can click on any school name to go to its schedule page.
How do I read the school schedule page?
The schedule at the top of the page shows the date and opponent for all scheduled games, and results for games already played. If results are missing, click “Submit Score” to add a game score.
Below the game schedule is the MPR Calculator. The calculator is split into three sections. The first section shows the three MPR component scores for the team, as well as the team’s current MPR score. The second section shows the MPR information for the team’s opponents – specifically, for the opponents the team already has played (actually, for games where scores have been submitted). Only these games are included in the MPR calculation. The third section highlights future opponents. The MPR data for future opponents is not used in the MPR calculation for the team.