Ratings Percentage Index for D1 College Hockey (2001-2002)

© 1999-2002, Joe Schlobotnik (archives)

URL for this frameset: http://slack.net/~whelan/tbrw/tbrw.cgi?2002/rpi.shtml

Game results taken from US College Hockey Online's Division I composite schedule

See also

Current RPI (including games of 2002 March 17)

Team RPI Record Sched Strength Opp Pct Opp Opp Pct RPIStr
Rk Rating Rk W-L-T Pct Rk SOS Rk OPct Rk OOPct Rk Rating
Denver U 1 .6259 1 32-7-1 .8125 20 .5254 24 .5204 1 .5420 1 .7451
Minnesota 2 .6241 4 29-8-4 .7561 2 .5530 3 .5587 7 .5339 3 .7105
New Hampshire 3 .6239 2 29-6-3 .8026 17 .5276 18 .5278 12 .5268 2 .7392
Boston Univ 4 .5991 8 25-9-3 .7162 11 .5361 12 .5377 9 .5307 7 .6750
St Cloud 5 .5947 6 29-10-2 .7317 25 .5210 26 .5162 3 .5370 6 .6820
Mich State 6 .5940 5 27-8-5 .7375 27 .5168 27 .5150 16 .5227 5 .6862
Maine 7 .5882 12 23-10-7 .6625 5 .5482 5 .5545 11 .5275 11 .6376
Michigan 8 .5826 9 26-10-5 .6951 22 .5220 23 .5211 14 .5252 9 .6550
CO College 9 .5824 11 26-12-3 .6707 13 .5349 14 .5348 6 .5353 10 .6394
Cornell 10 .5793 3 24-7-2 .7576 39 .4834 39 .4835 44 .4831 4 .6943
Mass-Lowell 11 .5611 14 22-13-3 .6184 15 .5302 17 .5327 18 .5218 14 .5986
AK-Fairbanks 12 .5607 13 22-12-3 .6351 26 .5206 25 .5197 15 .5235 13 .6085
Northern Mich 13 .5568 10 26-12-2 .6750 34 .4931 38 .4846 20 .5213 12 .6311
Mercyhurst 14 .5426 7 24-8-3 .7286 53 .4424 53 .4415 53 .4453 8 .6623
Western Mich 15 .5415 19 19-15-4 .5526 12 .5355 11 .5417 28 .5148 19 .5501
Ohio State 16 .5364 20 20-16-4 .5500 16 .5291 16 .5331 27 .5157 20 .5461
NE-Omaha 17 .5361 18 21-16-4 .5610 21 .5226 19 .5241 24 .5179 18 .5525
Northeastern 18 .5352 24 19-17-3 .5256 10 .5404 10 .5464 22 .5203 21 .5304
Wisconsin 19 .5190 34 16-19-4 .4615 4 .5500 4 .5560 10 .5300 30 .4833
Boston Coll 20 .5168 27 18-18-2 .5000 19 .5258 20 .5228 5 .5356 26 .5053
North Dakota 21 .5165 35 16-19-2 .4595 6 .5472 7 .5505 4 .5362 31 .4805
RPI 22 .5157 16 20-13-4 .5946 42 .4732 42 .4696 43 .4852 16 .5658
Wayne State 23 .5088 17 17-11-4 .5938 45 .4631 49 .4507 32 .5041 17 .5607
Clarkson 24 .5048 23 17-15-6 .5263 33 .4932 32 .4952 38 .4868 23 .5191
Quinnipiac 25 .5032 15 20-12-5 .6081 52 .4467 52 .4467 52 .4468 15 .5709
Providence 26 .5005 42 13-20-5 .4079 3 .5504 2 .5592 21 .5212 39 .4428
Harvard 27 .4999 26 15-14-4 .5152 35 .4916 33 .4928 35 .4878 25 .5100
Notre Dame 28 .4988 28 16-17-5 .4868 29 .5052 30 .5031 29 .5123 28 .4906
Ferris State 29 .4961 38 15-20-1 .4306 14 .5314 13 .5357 26 .5168 37 .4548
AK-Anchorage 30 .4956 43 12-19-5 .4028 8 .5456 8 .5491 8 .5338 40 .4366
Brown 31 .4852 30 14-15-2 .4839 38 .4859 37 .4856 37 .4868 29 .4843
Dartmouth 32 .4823 25 14-13-5 .5156 43 .4644 43 .4578 40 .4864 27 .5023
Minn-Duluth 33 .4822 47 13-24-3 .3625 7 .5467 6 .5527 13 .5266 45 .4064
Sacred Heart 34 .4806 22 16-14-4 .5294 49 .4543 46 .4559 51 .4490 24 .5125
AL-Huntsville 35 .4755 37 14-17-1 .4531 37 .4875 34 .4916 47 .4739 36 .4620
Holy Cross 36 .4753 21 15-12-5 .5469 54 .4368 54 .4355 55 .4411 22 .5212
MSU-Mankato 37 .4713 40 14-20-2 .4167 31 .5006 36 .4886 2 .5407 41 .4333
Air Force 38 .4711 33 12-14-2 .4643 41 .4748 41 .4764 48 .4695 34 .4671
Union 39 .4690 31 12-13-5 .4833 47 .4613 48 .4529 34 .4896 32 .4763
Miami 40 .4654 48 12-22-2 .3611 24 .5215 21 .5228 25 .5174 47 .3984
Niagara 41 .4643 32 14-16-1 .4677 46 .4624 47 .4555 42 .4856 35 .4649
Bemidji State 42 .4614 44 10-17-4 .3871 30 .5015 28 .5061 41 .4860 44 .4146
Colgate 43 .4612 41 13-19-2 .4118 36 .4878 35 .4899 46 .4806 42 .4298
Merrimack 44 .4557 51 11-23-2 .3333 23 .5216 22 .5214 17 .5220 50 .3767
Canisius 45 .4505 29 14-15-4 .4848 56 .4319 56 .4268 50 .4490 33 .4715
Michigan Tech 46 .4479 56 8-28-2 .2368 1 .5615 1 .5743 23 .5188 54 .3147
Bowling Green 47 .4477 52 9-25-6 .3000 18 .5272 15 .5336 31 .5062 52 .3539
Yale 48 .4467 49 10-19-2 .3548 32 .4961 31 .4987 36 .4876 49 .3880
Mass-Amherst 49 .4450 53 8-24-2 .2647 9 .5420 9 .5482 19 .5217 53 .3301
Iona 50 .4380 39 12-17-2 .4194 51 .4481 50 .4502 54 .4412 43 .4265
Princeton 51 .4367 45 11-18-2 .3871 44 .4633 44 .4575 45 .4830 46 .4033
Connecticut 52 .4343 36 13-16-7 .4583 58 .4214 58 .4122 49 .4520 38 .4477
Army 53 .4251 46 9-17-6 .3750 50 .4521 45 .4560 56 .4392 48 .3937
St Lawrence 54 .4217 50 11-21-2 .3529 48 .4587 51 .4468 33 .4983 51 .3746
Lake Superior 55 .4142 55 8-27-2 .2432 28 .5062 29 .5056 30 .5083 55 .3038
Vermont 56 .3574 59 3-26-2 .1290 40 .4804 40 .4784 39 .4868 59 .2097
American Intl 57 .3526 54 7-21 .2500 59 .4079 59 .3991 57 .4374 56 .2844
Fairfield 58 .3517 57 5-22-3 .2167 57 .4244 57 .4207 59 .4366 57 .2637
Bentley 59 .3360 58 4-26-2 .1562 55 .4327 55 .4314 58 .4372 58 .2197

Explanation of the Table

RPI
The Ratings Percentage Index is one of the NCAA's selection criteria for college hockey. It is a sum of .35 times a team's winning percentage, .50 times their opponents' winning percentage (q.v.) and .15 times their opponents' opponents' winning percentage (q.v.). Equivalently, it can be calculated as .35 times their winning percentage plus .65 times their Strength Of Schedule (SOS; q.v.).
Record
Winning percentage (Pct) is calculated as described on the rating system comparison page; in particular, it is calculated with a tie counting as half a win and half a loss.
Sched Strength
The Strength Of Schedule (SOS) as measured by RPI is given by 10/13 times a team's opponents' winning percentage (q.v.) plus 3/13 times their opponents' opponents' winning percentage (q.v.).
Opp Pct
The Opponents' Winning Percentage (OPct) for a team is calculated by averaging the winning percentages of all their opponents in games not involving that team. The weighting factor is the number of games a team played against a particular opponent. Because games against the team in question are left out, it is not simply a weighted average of the winning percentages.
Opp Opp Pct
The Opponents' Opponents' Winning Percentage (OOPct) for a team is a weighted average of the Opponents' Winning Percentages (OPct; q.v.) of each of their opponents. Once again, the weighting factor is the number of games played against each opponent, but this time no extra games are left out, so each opponent's contribution can be read from the OPct column for that opponent.
RPIStr
The "strength" of a team (as a prospective opponent) for RPI purposes is given by 10/13 times their winning percentage plus 3/13 times their Opponents' Winning Percentage (OPct; q.v.). Since head-to-head games have to be left out of the RPI calculation, a team's strength of schedule is not exactly the weighted average of the RPIStr numbers for all its opponents, but RPIStr gives a sense of how RPI will evaluate the strength of each opponent. (Each team's name in the table above is a link to a rundown of selection criteria which includes a list of their opponents with their actual contribution to that team's strength of schedule.) Note that RPIStr is much more heavily weighted towards winning percentage than RPI itself.

The Nitty-Gritty

The definitions above provide all the information needed to calculate the RPI, but to spell out the formula explicitly, if Vij is the number of times team i has beaten team j (with ties as always counting as half a win and half a loss), Nij=Vij+Vji is the number of times they've played, Vi=∑jVij is the total number of wins for team i and Ni=∑jNij is the total number of games they've played, then team i's RPI is given by

0.35*Vi/Ni + 0.50 * ∑j(Nij/Ni)*(Vj-Vji)/(Nj-Nji) + 0.15 * ∑j(Nij/Ni)*[∑k(Njk/Nj)*(Vk-Vkj)/(Nk-Nkj)]

Some Background

The RPI was developed for general-purpose use within the NCAA over the course of the past couple of decades. The original definition, still used outside of hockey, has slightly different weightings of the terms at 25, 50, and 25 percent for Winning Percentage, Opponents' Winning Percentage, and Opponents' Opponents' Winning Percentage, respectively. However, the impact of strength of schedule on the ratings meant it was possible for a team to hurt its RPI by playing a weak opponent, even if they won the game. (Specific examples of this from the 1994-1995 season were Colorado College vs Air Force and Bowling Green vs Ohio State. In the latter case BGSU split two non-conference games with OSU and fell just short of making the NCAAs; if they had won both games, they still would have missed the tournament, but not playing them at all would have improved their RPI enough to get an at-large bid.) Presumably in response to this, the weighting of the terms in college hockey's RPI was changed to the current 35/50/15.

Shortcomings of RPI

A more extreme problem with the RPI was brought to light in the 1998-1999 season, when the Metro-Atlantic Athletic Conference (MAAC) began play and six more Division I teams were suddenly eligible for the NCAAs. Because they played most of their games against each other, the winning percentages which contributed to their strength of schedule were on average not much worse that those of the rest of the NCAA, even though those out of conference games that were played indicated that, top-to-bottom, the MAAC was nowhere near as strong as the other conferences. (The revised weighting, with increased improtance given to a team's own winning percentage, only exacerbated the situation.) This led to the fact that in the first two years of competition, MAAC regular season champion Quinnipiac ended up in the top 12 in the nation according to the RPI by compiling a high winning percentage against a mostly MAAC schedule. The NCAA selection committee anticipated this at the beginning of the MAAC's first season, and reserved the right to overrule RPI and the other selection criteria if it judged based on "overall conference strength" that there was a lack of "competitive equity" between conferences.

Alternatives to RPI

It was observed at the time that while Quinnipiac, for reasons described above, was rated significantly higher than they should have been by the RPI, several other rating systems ranked them much lower down, where it was felt they deserved to be. Many of the other ranking systems, like CHODR, CCHP, and Massey, take into consideration factors, like margin of victory and/or home ice, which are deliberately ignored by the RPI. The HEAL and RHEAL rating systems, while only considering won-lost-tied outcomes of each game, make distinctions based on which of a team's games it won or lost (so that beating a good team and losing to a bad team will get you more highly ranked than losing to a good team and beating a bad team).

One ranking system which, like the RPI, considers only a team's overall winning percentage and the strengths of the teams they played, is the Bradley-Terry ranking system, which goes under the name of KRACH when applied to college hockey. KRACH has been described as a system which does correctly what RPI is intended to do: provide a rating which evaluates a team's won-lost-tied performance over the entire season, taking into account the strength of their schedule. Much more on this system can be found at our KRACH page.


Last Modified: 2012 March 25

Joe Schlobotnik / joe@amurgsval.org

HTML 4.0 compliant CSS2 compliant