Bumped from the diaries. While I understand there may be legit arguments against using RPI as a measuring standard, give how it is used in the national discussions on college hoops, bruinhoo's diary is a must read. GO BRUINS. -N
Crossposted and edited from last night's postgame thread.
Talk of which conference is the best in college basketball this season has been a popular pastime over the past several weeks, among fans as well as the columnists and talking heads that make their living covering the sport. The "best conference" debate is very much an open question; while most have placed either the Pac-10 or the Big East in the #1 spot, the ACC has again gotten some love (particularly from the WWL), based upon its having the highest conference RPI. On ESPN's College Game Night program airing after last night's game, the pro-ACC argument was made, with an added attack on the argument in favor of the Pac-10, that the teams in the middle of the conference (places 4-9) are overrated; the fact that middle-to-lower level teams beatup on one another is being used as an excuse for the large number of these teams (with conference records ranging near .500) being considered viable NCAA contenders.
While the piece last night was motivation for me to actually write something about the vagarities of using conference average RPI, and the resulting RPI rankings of conferences as a determination of relative strength, the idea that I have here, that an outlying team (good or bad) can have a notable effect on the RPI's determination of conference strength has been on my mind for some time. In terms of the Pac-10, the conference currently rates 3rd in conference RPI, but is hindered in this respect by the unmatched ineptitude of Oregon State (as well as placing in "worst Pac-10 team ever discussions, with an RPI rank approaching #250, the team is by far the worst team in a power conference this year, and over 130 places below the next lowest RPI team in the conference, Washington.) which is often not factored in by those using the conference RPI rankings for comparison.
Using Ken Pomeroy's RPI calculations (as posted on 2/28, taking into account games played through 2/27), I took the average conference RPI for the 6 highest rated conferences, then removed the single best and worst RPI-ranked team from each conference in order to get an idea of the comparative strength of the conferences once any outlying teams are discarded.
Raw Conference RPI
- ACC: .5793
- Big XII: .5726
- Pac-10: .5721
- Big East: .5690
- SEC: .5663
- Big 10: .5519
Recalculated conference RPI
- Pac-10: .5790
- ACC: .5757
- Big XII: .5709
- Big East: .5709
- Big 10: .5522
- SEC: .5487
Teams removed in recalculationNote: Conference RPI is the sum of the RPI ratings of each team in a conference (ie. UCLA's RPI rating was .6375, good for the #9 overall ranking) divided by the number of teams in that conference. The recalculated RPI subtracts the RPI rating of the teams with the single best and single worst rating in the conference, and divides the remaining sum by the remaining number of teams in the conference (ie. UCLA and Oregon St's RPI rating was subtracted from the combined rating of all Pac-10 teams, that figure was then divided by the 8 teams remaining.).
- Pac-10: UCLA (RPI #9), Oregon State (RPI #247)
- ACC: Duke (#3), Virginia (#120)
- Big XII: Texas (#4), Colorado (#162)
- Big East: Georgetown (#10), Rutgers (#205)
- Big 10: Wisconsin (#13), Northwestern (#206)
- SEC: Tennessee (#1), LSU (#164)
As you can see, the effect of dropping Oregon State from the Pac-10's RPI has a heavy comparative effect in the conference's stature; even with the corresponding loss of UCLA at the top, the Pac-10 becomes the clear #1 when all but the best and worst single teams are considered. The ACC loses its place at the top primarily because its normally calculated conference RPI is not thrown off by a single negative outlier as the Pac-10, and to a lesser extent the Big East and Big 10 are (Virginia is clearly the 'best' last-place team of the power conferences, with a #120 RPI and bruinhoo among its grad students). The SEC, already in the lower tier of the top conferences, suffers greatly from the loss of #1 Tennessee from consideration.
Comparison of the conference RPI's with and without the first and last place teams shows that the SEC actually possesses the greatest outlier, in RPI #1 Tennessee. The Pac-10 gains the most from losing the negative outlier that is Oregon State; the Big East and Big 10 see modest bumps that may be attributed to losing the effect of sub 200-RPI teams Rutgers and Northwestern, respectively. The Big XII experiences a fall as the loss of Colorado at the bottom is not fully balanced by the loss of Texas at the top.