Essentially, all it's doing is asking 'If Team X has a RPI of 100, did they outperform or underperform expectations for team with that RPI and that schedule. A team that won more games than expected for its RPI would have a pretty strong case that its rating was too low. A team that lost more games than expected for its RPI would be viewed as being rated too high. This is basically what I do with the Colton Index, only I start with the win-loss record and do multiple iterations of the expectations and performance relative to expectations until the complete ranking set is as correct as it can be. The RPI+ proposal uses just one iteration of the performance component (although additional iterations would only make it better). You'll see in a minute that just one iteration does have a significant impact. Also, because you can capture the home-road adjustments more accurately in the performance component, you really wouldn't need to do the crude 40% home/road adjustment upfront. You'd be better off just using the old RPI and let the home/road show up in the performance component. However, I used the new RPI here simply because it makes for easier comparison of teams that would be most impacted.
The other proposed change is to finally abandon the deeply flawed, linear RPI SOS measure. Since we are calculating expected winning percentage for the performance component, it's easy to implement here. The proposed SOS captures the home/road influence accurately and recognizes that SOS is not linear (playing the 1st, 2nd and 330th ranked teams on the road IS NOT the same as playing the 110th, 111th and 112th rated teams at home).
Below is the new RPI and RPI+ for the top 90 RPI teams plus 6 teams who would be top 90 under RPI+. The 'Exp Wins' column shows the Expected Number of Wins for a team with that RPI given its schedule. So Tennessee would be expected to win 28.11 with its schedule if it were the #1 RPI team. Since they won 28 games, you'd expect their 'true' ranking to be slightly lower than that. The far right column shows the expect number of wins in the second iteration (if you account for the change in a team's rating for RPI+ and the change in the rating of all its opponents). I only show it here for information purposes, so you can get some sense directionally which way teams would go if you added additional performance iterations. The top 20 overperformers relative to RPI are shaded in yellow. The top 20 underperformers relative to RPI are shaded in orange.
Just adding the one performance components is a huge improvement in the RPI. The wins versus expectations are off by an average of 0.89 wins per team in the new RPI. Adding that one performance component brings that number down to 0.34 (the Colton Index is off by 0.04 per team). The other way I like to look at these rankings is by measuring the amount of informational lift that ranking provides over the most simple rank order you could think of...simply sorting teams by their win-loss record. We use alternative rankings because we know win-loss record doesn't tell the full story. Presumably, the ranking is a more accurate reflection of what's going on during the course of a basketball season, otherwise we wouldn't use it. Therefore, it's easy to measure different rating systems on how much additional value they provide.
Traditionally, the new RPI has been about 5-6% worse than the old RPI, and the Colton Index has provided 40-50% more lift versus the baseline relative to the new RPI. The 2007-08 season is no exception. I know it's hard to believe, but the old RPI is 5.2% better than the new RPI. The Colton Index outperforms the new RPI by 44%. RPI+ is 33.5% better than the new RPI. This seems like an easy fix that would provide the Selection Committee with significantly better information to make their decisions.
A couple teams to note from the table below:
- Vanderbilt seemed to be overseeded as a 4 seed, and we see their performance was over a game worse than expected from that lofty 12th-rated RPI. The 2nd iteration would suggest they would go down even futher with additional iterations. UNLV is another team that seemed to be overseeded as well.
- The Selection Committee doesn't seem to have much faith in very strong RPI numbers for mid-majors (see Southern Illinois last year). Butler seemed to suffer from this bias this year, although the RPI+ numbers suggest they outperformed their 17th-rated RPI.
- Arizona St is one of the biggest movers amongst tourney or bubble teams. They move up 30 spots when you consider they outperformed their RPI rating by 1.73 games. Also, by moving away from the linear nature of SOS, the 'bottom feeders' in their non-conference schedule don't hurt as much and their SOS increases from 77 to 32.
- South Alabama doesn't move in RPI+ (they would move down in future iterations), but just check out that SOS impact. 127 vs 203.
| EXP WINS | RANK | SOS | EXP WINS2 | |||||||
| TEAM | W | L | RPI | RES | RPI | RPI+ | RPI | RPI+ | RPI+ | RES2 |
| Tennessee | 28 | 4 | 28.11 | -0.11 | 1 | 3 | 1 | 8 | 28.30 | -0.30 |
| North Carolina | 32 | 2 | 30.51 | 1.49 | 2 | 1 | 3 | 21 | 31.46 | 0.54 |
| Memphis | 33 | 1 | 31.29 | 1.71 | 3 | 2 | 27 | 115 | 32.28 | 0.72 |
| UCLA | 30 | 3 | 28.32 | 1.68 | 4 | 4 | 14 | 22 | 29.42 | 0.58 |
| Kansas | 30 | 3 | 28.90 | 1.10 | 5 | 5 | 50 | 72 | 29.68 | 0.32 |
| Texas | 27 | 6 | 27.25 | -0.25 | 6 | 8 | 4 | 6 | 26.97 | 0.03 |
| Duke | 27 | 5 | 26.49 | 0.51 | 7 | 6 | 8 | 10 | 26.89 | 0.11 |
| Georgetown | 27 | 5 | 26.44 | 0.56 | 8 | 7 | 32 | 43 | 26.97 | 0.03 |
| Xavier | 27 | 6 | 27.34 | -0.34 | 9 | 11 | 24 | 55 | 27.50 | -0.50 |
| Drake | 26 | 4 | 25.35 | 0.65 | 10 | 10 | 68 | 92 | 26.03 | -0.03 |
| Wisconsin | 29 | 4 | 27.33 | 1.67 | 11 | 9 | 61 | 86 | 28.50 | 0.50 |
| Vanderbilt | 26 | 7 | 27.12 | -1.12 | 12 | 17 | 41 | 83 | 26.55 | -0.55 |
| Louisville | 24 | 8 | 24.50 | -0.50 | 13 | 14 | 6 | 23 | 24.02 | -0.02 |
| Stanford | 26 | 7 | 25.06 | 0.94 | 14 | 13 | 56 | 29 | 25.72 | 0.28 |
| Pittsburgh | 25 | 9 | 25.03 | -0.03 | 15 | 15 | 20 | 12 | 24.92 | 0.08 |
| Michigan St | 25 | 8 | 25.58 | -0.58 | 16 | 22 | 43 | 58 | 24.80 | 0.20 |
| Butler | 29 | 3 | 27.40 | 1.60 | 17 | 12 | 128 | 156 | 28.88 | 0.12 |
| Connecticut | 24 | 8 | 24.10 | -0.10 | 18 | 21 | 35 | 40 | 23.74 | 0.26 |
| Clemson | 23 | 9 | 22.91 | 0.09 | 19 | 20 | 17 | 19 | 22.91 | 0.09 |
| Marquette | 23 | 9 | 22.50 | 0.50 | 20 | 19 | 21 | 15 | 22.81 | 0.19 |
| Kent St | 28 | 6 | 27.73 | 0.27 | 21 | 24 | 111 | 140 | 28.24 | -0.24 |
| Indiana | 25 | 7 | 24.49 | 0.51 | 22 | 23 | 59 | 80 | 25.10 | -0.10 |
| Washington St | 24 | 8 | 22.72 | 1.28 | 23 | 16 | 46 | 25 | 23.61 | 0.39 |
| UNLV | 25 | 7 | 26.17 | -1.17 | 24 | 34 | 63 | 141 | 25.48 | -0.48 |
| BYU | 27 | 7 | 26.78 | 0.22 | 25 | 25 | 97 | 122 | 27.30 | -0.30 |
| Notre Dame | 24 | 7 | 22.76 | 1.24 | 26 | 18 | 81 | 67 | 23.89 | 0.11 |
| Oklahoma | 22 | 11 | 22.16 | -0.16 | 27 | 31 | 13 | 24 | 21.88 | 0.12 |
| Southern California | 21 | 11 | 20.68 | 0.32 | 28 | 27 | 9 | 3 | 20.49 | 0.51 |
| West Virginia | 23 | 10 | 22.64 | 0.36 | 29 | 28 | 45 | 33 | 22.85 | 0.15 |
| Gonzaga | 25 | 7 | 23.92 | 1.08 | 30 | 26 | 93 | 102 | 24.99 | 0.01 |
| EXP WINS | RANK | SOS | EXP WINS2 | |||||||
| TEAM | W | L | RPI | RES | RPI | RPI+ | RPI | RPI+ | RPI+ | RES2 |
| Arkansas | 22 | 11 | 23.29 | -1.29 | 31 | 40 | 25 | 59 | 21.98 | 0.02 |
| Dayton | 21 | 10 | 22.39 | -1.39 | 32 | 42 | 33 | 78 | 21.16 | -0.16 |
| Illinois St | 23 | 9 | 23.85 | -0.85 | 33 | 39 | 71 | 93 | 22.84 | 0.16 |
| Miami (FL) | 21 | 10 | 21.22 | -0.22 | 34 | 36 | 42 | 48 | 21.01 | -0.01 |
| Davidson | 25 | 6 | 24.43 | 0.57 | 35 | 30 | 129 | 150 | 24.96 | 0.04 |
| St. Mary's | 24 | 6 | 23.28 | 0.72 | 36 | 29 | 138 | 145 | 24.16 | -0.16 |
| Arizona | 18 | 14 | 19.27 | -1.27 | 37 | 46 | 2 | 1 | 17.19 | 0.81 |
| South Alabama | 24 | 6 | 24.19 | -0.19 | 38 | 37 | 127 | 203 | 24.60 | -0.60 |
| Western Kentucky | 25 | 6 | 24.62 | 0.38 | 39 | 35 | 142 | 201 | 25.53 | -0.53 |
| Mississippi St | 22 | 10 | 22.33 | -0.33 | 40 | 41 | 58 | 85 | 22.26 | -0.26 |
| Texas A&M | 23 | 10 | 21.99 | 1.01 | 41 | 33 | 52 | 56 | 23.06 | -0.06 |
| Massachusetts | 21 | 10 | 21.31 | -0.31 | 42 | 43 | 70 | 84 | 21.17 | -0.17 |
| Baylor | 20 | 10 | 19.71 | 0.29 | 43 | 38 | 49 | 54 | 19.98 | 0.02 |
| Saint Joseph's | 21 | 12 | 21.55 | -0.55 | 44 | 48 | 53 | 60 | 21.23 | -0.23 |
| Purdue | 24 | 8 | 22.58 | 1.42 | 45 | 32 | 114 | 98 | 23.89 | 0.11 |
| Creighton | 20 | 10 | 20.40 | -0.40 | 46 | 50 | 66 | 79 | 19.96 | 0.04 |
| Temple | 21 | 12 | 22.15 | -1.15 | 47 | 58 | 51 | 73 | 20.65 | 0.35 |
| Mississippi | 21 | 10 | 21.31 | -0.31 | 48 | 49 | 65 | 91 | 21.07 | -0.07 |
| Ohio State | 19 | 13 | 19.61 | -0.61 | 49 | 54 | 18 | 27 | 18.70 | 0.30 |
| Kansas St | 19 | 11 | 19.33 | -0.33 | 50 | 51 | 34 | 51 | 18.61 | 0.39 |
| Villanova | 20 | 12 | 19.78 | 0.22 | 51 | 45 | 47 | 39 | 20.04 | -0.04 |
| Virginia Tech | 19 | 13 | 19.98 | -0.98 | 52 | 63 | 39 | 38 | 18.45 | 0.55 |
| Oral Roberts | 23 | 8 | 23.72 | -0.72 | 53 | 59 | 157 | 191 | 23.56 | -0.56 |
| VCU | 24 | 7 | 23.61 | 0.39 | 54 | 44 | 161 | 189 | 24.45 | -0.45 |
| Syracuse | 19 | 13 | 19.68 | -0.68 | 55 | 61 | 10 | 34 | 18.50 | 0.50 |
| UAB | 22 | 10 | 23.56 | -1.56 | 56 | 70 | 95 | 155 | 22.12 | -0.12 |
| Kentucky | 18 | 12 | 18.03 | -0.03 | 57 | 55 | 19 | 41 | 18.02 | -0.02 |
| Oregon | 18 | 13 | 18.02 | -0.02 | 58 | 56 | 37 | 9 | 17.36 | 0.64 |
| New Mexico | 24 | 8 | 23.14 | 0.86 | 59 | 47 | 155 | 165 | 24.51 | -0.51 |
| Florida St | 19 | 14 | 19.11 | -0.11 | 60 | 60 | 15 | 16 | 18.49 | 0.51 |
| EXP WINS | RANK | SOS | EXP WINS2 | |||||||
| TEAM | W | L | RPI | RES | RPI | RPI+ | RPI | RPI+ | RPI+ | RES2 |
| George Mason | 23 | 10 | 24.79 | -1.79 | 61 | 83 | 126 | 211 | 23.20 | -0.20 |
| Southern Illinois | 17 | 14 | 18.40 | -1.40 | 62 | 77 | 16 | 42 | 16.09 | 0.91 |
| Cleveland St | 19 | 12 | 20.40 | -1.40 | 63 | 86 | 85 | 105 | 18.65 | 0.35 |
| Stephen F. Austin | 22 | 5 | 21.21 | 0.79 | 64 | 52 | 263 | 297 | 22.42 | -0.42 |
| Cornell | 21 | 5 | 20.62 | 0.38 | 65 | 62 | 265 | 292 | 21.35 | -0.35 |
| Siena | 22 | 10 | 23.09 | -1.09 | 66 | 85 | 120 | 179 | 22.21 | -0.21 |
| Georgia Tech | 15 | 17 | 15.70 | -0.70 | 67 | 76 | 7 | 2 | 14.43 | 0.57 |
| Charlotte | 20 | 13 | 20.17 | -0.17 | 68 | 71 | 64 | 95 | 20.12 | -0.12 |
| IUPUI | 23 | 7 | 23.19 | -0.19 | 69 | 73 | 238 | 277 | 23.44 | -0.44 |
| Utah St | 23 | 10 | 24.93 | -1.93 | 70 | 102 | 168 | 267 | 23.44 | -0.44 |
| Florida | 21 | 11 | 19.92 | 1.08 | 71 | 57 | 87 | 94 | 21.22 | -0.22 |
| Miami (OH) | 17 | 15 | 17.93 | -0.93 | 72 | 89 | 54 | 50 | 16.83 | 0.17 |
| Nevada | 20 | 11 | 21.53 | -1.53 | 73 | 100 | 132 | 161 | 20.18 | -0.18 |
| Texas Tech | 15 | 15 | 15.65 | -0.65 | 74 | 84 | 5 | 7 | 14.46 | 0.54 |
| Akron | 23 | 10 | 22.53 | 0.47 | 75 | 65 | 135 | 157 | 23.37 | -0.37 |
| Ohio | 19 | 12 | 20.07 | -1.07 | 76 | 94 | 109 | 123 | 18.94 | 0.06 |
| Rhode Island | 21 | 11 | 20.47 | 0.53 | 77 | 64 | 107 | 124 | 21.27 | -0.27 |
| Oklahoma St | 16 | 15 | 15.94 | 0.06 | 78 | 72 | 12 | 11 | 15.85 | 0.15 |
| Belmont | 24 | 8 | 24.46 | -0.46 | 79 | 82 | 229 | 293 | 24.81 | -0.81 |
| CS Fullerton | 23 | 8 | 23.29 | -0.29 | 80 | 79 | 199 | 249 | 23.24 | -0.24 |
| Houston | 22 | 9 | 21.62 | 0.38 | 81 | 69 | 146 | 171 | 22.31 | -0.31 |
| San Diego St | 19 | 12 | 19.80 | -0.80 | 82 | 90 | 99 | 118 | 19.00 | 0.00 |
| Arizona St | 19 | 12 | 17.27 | 1.73 | 83 | 53 | 77 | 32 | 18.58 | 0.42 |
| Austin Peay | 24 | 10 | 26.00 | -2.00 | 84 | 116 | 205 | 288 | 25.12 | -1.12 |
| Maryland | 18 | 14 | 18.05 | -0.05 | 85 | 80 | 31 | 63 | 17.89 | 0.11 |
| Wright St | 21 | 10 | 20.21 | 0.79 | 86 | 66 | 149 | 144 | 21.35 | -0.35 |
| Boise St | 24 | 8 | 23.59 | 0.41 | 87 | 74 | 196 | 276 | 24.61 | -0.61 |
| UMBC | 23 | 8 | 23.57 | -0.57 | 88 | 95 | 264 | 302 | 23.57 | -0.57 |
| UC Santa Barbara | 22 | 8 | 21.62 | 0.38 | 89 | 75 | 208 | 221 | 22.33 | -0.33 |
| American | 21 | 11 | 22.58 | -1.58 | 90 | 120 | 158 | 237 | 21.48 | -0.48 |
| California | 16 | 15 | 15.51 | 0.49 | 92 | 81 | 28 | 14 | 15.61 | 0.39 |
| Nebraska | 19 | 12 | 17.39 | 1.61 | 96 | 68 | 94 | 69 | 18.72 | 0.28 |
| Wake Forest | 17 | 13 | 15.26 | 1.74 | 100 | 67 | 86 | 52 | 17.20 | -0.20 |
| Minnesota | 20 | 13 | 18.75 | 1.25 | 101 | 78 | 113 | 87 | 20.03 | -0.03 |
| Providence | 15 | 16 | 13.62 | 1.38 | 112 | 87 | 44 | 17 | 15.09 | -0.09 |
| Washington | 16 | 16 | 14.06 | 1.94 | 121 | 88 | 60 | 18 | 15.78 | 0.22 |










