just like the BCS rankings nobody knows really how they're calculated they just accept them..
Are the RPI Rankings An Accurate Measure of Basketball Team Strength?
albeit with a lot of data behind it.
where WP is Winning Percentage, OWP is Opponents' Winning Percentage and OOWP is Opponents' Opponents' Winning Percentage.
Or if you prefer, see Ken Pomeroy's summary
I am almost certain one could find a measure that provides a better predictor of future wins. Nonetheless, Ken Pomeroy defended it here (scroll way down to see beginning of the post long ago in comparison to the early BCS methodology, which kept USC out of the title game in 2003
And considering its simplicity, the RPI is pretty good at what it's supposed to do. Winning games is good, playing a tough schedule is good. But more fundamentally, just being a good team is good. There’s really no easy way to cheat the system. And even if you could, there is a bunch of humans waiting at the end of the season to try to smooth out the problems.
Posted on 12/26 at 01:20 AM
Beat me to it.
A home win now counts as 0.6 win, while a road win counts as 1.4 wins. Inversely, a home loss equals 1.4 losses, while a road loss counts as 0.6 loss. A neutral game counts as 1 win or 1 loss. Note that this location adjustment applies only to the WP factor and not the OWP and OOWP factors. Only games against Division 1 teams are included for all RPI factors.
Why is the multiplier for winning % .25 while the opponents winning % is .5?
Because winning percentage varies much more than opponents' winning percentage.
For example, the best teams have a winning percentage of about .900, the worst have winning percentages of about .100. Opponents' winning percentage only varies from about .400 to about .600. So the best teams get (.900 x .25) = .225 RPI points for their winning percentage and the worst teams get (.100 x .25) = .025 RPI points for their winning percentage. About a .200 difference between the best and worst teams.
But in opponents' winning percentage (OWP), the teams with the strongest schedules get (.600 x .5) = .300 RPI points for their OWP, and the teams with the weakest schedules get (.400 x .5) = .200 RPI points for their OWP.
So even though the factor for winning percentage is only .25 and the factor for opponents' winning percentage is .50, really the difference between the best and worst teams is about twice as big for winning percentage compared with OWP. You could say that winning percentage is weighted about twice as heavily as opponents' winning percentage, when variance is taken into account.
Logged in just to upvote you. Extremely good post. Very well thought-out and explained. Thank you.
The RPI is actually a really dumb formula that is intentially dumbed down so that most people who care to learn the formula can easily understand it.
What they should actually shoot for is a ratings index that is the best predictor of future results based on wins and losses alone. This would require lots of fancy math and statistics, so it's not going to happen. The NCAA prefers a system that slaps randomly chosen factors to opponents and opponents-opponents win-loss record because it's easy to compute.
Exactly--the big problem is that RPI was created in the late 1970s, about 5-10 years before home computers became ubiquitous. It was therefore determined that a linear calculation was preferable, rather than a matrix-based or iterated calculation, even though the math makes much more sense with a matrix-based formula.
So the real problem is that they had to use a suboptimal approach to rating, in order to appease the athletic department people who wanted to be able to check the NCAA's math without using a computer.
The best predictive systems often rate teams higher than they deserve to be based on their actual accomplishments. For instance, Sagarin's post-national championship game predictive system ranks Auburn 5th, even though they won the national titile. Alabama, by contrast, is ranked 3rd. Oregon is ranked 2nd, and Stanford is ranked 1st. In college basketball, Kenpom ranks Clemson 38th, despite their middling schedule, a few poor losses, and their best win coming over #40 FSU. The reason for both of these oddities is that Clemson and the teams ranked above Auburn lost relatively close games and won a number of games by wide margins. This is important because margin of victory or defeat is generally a better predictive measure than who actually wins or loses a game.
This is a problem area when deciding who is actually more deserving of a tournament spot. On one hand, it is obviously better to beat a team by 20 than to beat them by 2. On the other hand, if Team A wins beats two teams by a margin of 5 points apiece and Team B beats one of them by 15 and loses the other by 1, I doubt anyone would say that Team B is more deserving of a bid than Team A as the ultimate goal in team sports is to win, and the margin of a victory is a secondary concern.
A friend and I were noticing things like you did just a few days ago. The RPI rankings are full of oddities like that.
They have Belmont at #31.
KenPom is a better ranking because they strip it down to tempo free stats IMO.
It was probably because of their big win over Kennesaw State. All great teams need a signature win and you simply can't take that on away from the mighty Belmont Bruins.
take account into strength of schedule. With that being said, if you dominate your competition, you deserve to be ranked high at #31 which Belmont is.
They blew out most of the teams in their schedule which is why they're 24-4 and is a favorite to win Atlantic Sun conference.
It helps when you win nearly every game you play.
It's certainly not everything but it works as a basic indicator. The key with RPI is that you really need to look at SOS at the same time.
Michigan- RPI: 61 SOS: 18
Belmont- RPI: 53 SOS: 230
So yes, Belmont has a slightly better RPI but the SOS has to be considered. If resumes were based on this alone, Michigan would far and away be more impressive.
this is why the wisky game is so important. a W would mean a decent jump in rpi. our strength of schedule will also jump after the final 3 games.
that said, the rpi is too simplistic a formula. at least the BCS considers several formulas to attempt to eliminate any strange bias of a single formula.
For college basketball, here is how you calculate RPI:
RPI = Winning Percentage * 0.25 + Opponents' Winning Percentage * 0.5 + Opponents' Opponents' Winning Percentage * 0.25.
Winning percentage is adjusted for road and home advantages. Home wins count as 0.6 wins, home losses count as 1.4 losses, road wins count for 1.4 wins, road losses count for 0.6 losses. Neither opponents' winning percentage nor opponents' opponents' winning percentage is calculated with this adjustment.
Opponents' winning percentage is also adjusted to remove any games you play. So if you beat a team, you do not reduce your opponents winning percentage for the purpose of the RPI. Opponents' opponnents' winning percentage, on the other hand, does not remove any games from consideration.
The reason that Belmont's RPI is higher than Michigan's (albeit very slightly) is simple. While Belmont has faced a weak schedule, their winning percentage as calculated by the RPI is very high as they have played a lot of games on the road and won a lot of them too. Meanwhile, they have home losses to drag down their winning percentage.
The biggest issue with the RPI, in my opinion, is that it does not care whether you have any quality wins. That is why the NCAA considers quality wins an additional item to consider alongside RPI when deciding who goes to the tournament.
Change "Are" to "Is" so you don't look like a dumbass.
Coming from a guy who proudly stalks players and recruits on the internet?
I'd hate to hear what you have to say about Tim. This site really is full of morons. I'll keep posting to even it out with my supreme intellect.
Why thank you for the excellent grammar tip. I appreciate you looking out for me.
But weren't YOU the guy yesterday accusing me of belittling other posters and generally feeling superior to other people? How ironic.
The level to which you took it can not be put in the same category. You ARE an epic douche.
Hey Fuckwad.....I mean Larry:
I've sat quietly and taken your shit long enough. I'm not quite sure which one of the politically correct edicts I broke to so incur your rightious indignation but I've had enough of it. So here's a summary of the score to date:
I've got three kids who love me (the most important thing I have). I would be shocked if you had any clue what fatherhood was like
I've got a far better job than you (own my own company with 250+ employees and are moving forward with an IPO in spring 2012)
I've got way cooler toys than you (just bought a CTS-V yesterday...it's awesome)
I've got a WAY hotter wife than you who also loves me (see my avatar for proof)
I've got lots of friends
I am actively involved in my church, serve on three charitable boards and go to inner city Cleveland Sunday nights to feed the homeless.
So while I cant speak for the entire board I guess I do think i'm better than you. Go fuck yourself Larry or Busey or whatever the hell you call yourself.
Truth is a bitch asshole.
The current state of MGoBoard distilled into one perfect post.
GET OUT YOUR RULERS AND UNZIP YOUR PANTALOONS
IT'S MEASURING TIME
What if you're all grow and no show?
Hey Faggots, My name is John, and I hate every single one of you. All of you are fat, retarded, no-lifes who spend every second of their day looking at stupid ass pictures. You are everything bad in the world. Honestly, have any of you ever gotten any pussy? I mean, I guess it's fun making fun of people because of your own insecurities, but you all take to a whole new level. This is even worse than jerking off to pictures on facebook.
Don't be a stranger. Just hit me with your best shot. I'm pretty much perfect. I was captain of the football team, and starter on my basketball team. What sports do you play, other than "jack off to naked drawn Japanese people"? I also get straight A's, and have a banging hot girlfriend (She just blew me; Shit was SO cash). You are all faggots who should just kill yourselves. Thanks for listening.
I'm tired of taking that idiots shit. Sue me.
If you were my boss, I'd quit my job. Just sayin'
I'll bet you wouldnt. We run an inside sales department and the average income is 90k. If you quit you'd be the first.
You do understand that your awesomeness does not preclude others using this awesome thing called the internet from also having awesomeness correct?
My post wasn't directed at you so I'm not quite sure how it managed to offend you unless you're Larry. He has made several disparaging remarks about me as a person and in real life I do kick his ass. I made zero claims to be more awesome than one guy.
I DRIVE A DODGE STRATUS!
Whoa, I was unaware that Rush Limbaugh was roaming the MGOBoard.
Wow, Larry. You certainly have come a long way from the days when you were the guy with the "morans" sign. Congrats on your "supreme intellect."
He pluralized rankings and there are multiple RPI ranks. Now you look like a dumbass.
Change "Are" to "Is" so you don't look like a
+10000 for excellent thread title. All other posters take notice, this is how you title a post.
At the end of the day, if you're record is 24-4, you're always going to have a solid computer ranking. Think of the BCS, undefeated teams are usually very high in the computers regardless of who they've been. A teams record is always a substantial part of these rankings.
I guess that's my point. Playing cupcake U....and winning....seems to give teams a favorable RPI ranking. And given that the RPI. not SOS, is the metric most commonly quoted when evaluating a teams tourny chances I'm questioning its validity. As someone accurately pointed out, our SOS is one of the nation's best (thanks Big 10) yet we are barely mentioned as a bubble team, much less in, because of our poor RPI.
Doesnt seem right to me.
that team will probably end up winning 30 games, including their conf tourney. I'm fine with them having a better RPI than a mediocre M team.
If at season's end the RPI is sub 50 that will help M's chances. RPI is mentioned a lot but almost always in connection with SOS. Should be an interesting finish to the season.
As an at-large, Belmont's tourney chances aren't better than Michigan's. The committee likes to use RPI, but not simply as 'team with RPI 57' > 'team with RPI 58'. Record vs top 25 and top 50 teams by RPI matter a lot, and Belmont's 0-3 record vs the top 50 almost certainly keeps them from getting an at-large spot
And given that the RPI. not SOS, is the metric most commonly quoted when evaluating a teams tourny chances I'm questioning its validity.
SOS is part of the RPI formula. Our SOS is the reason our RPI is as high as it is. 17-11 probably isn't even one of the 100 best records in the country.
So perhaps we should schedule the Oakland U game at their barn in the future.
Seems to me haven't we played them at the Palace a few times? I think MSU has, too.
They played a hat, for god's sake. Well, maybe it was a ten gallon hat. Plus the cologne. Ok, I'm cool with the rating.
Don't forget they played these guys too.....twice.
I have much less an issue with a 24-4 team with some recent success in the tourney having a chance getting in over a mediocre Cincy or WVU team getting in because they play in the BE. RPI is imperfect, but I do think it gives a decent snapshot of how good teams are.