Not Well-Adjusted
11.02.04
It's time to look at the adjusted RPI. I don't like bashing Joe Lunardi, because he's the closest thing we have to a stats guy in the mainstream media, even though he's very far away from where we should be. And actually this won't be "bashing". Please consider it a thoughtful critique. After all, I fully realize someone could rip apart many things I have written. Before I get into the guts of the adjusted RPI, where road wins count more than other wins, I have to jump on some things in Lunardi's most recent column on the subject...
In other words, a win at Duke in February will count just a little more than a homecourt thumping of Prairie View in December.
Lunardi fails to mention that a last-second win at Prairie View will count more that a blowout home win vs. Duke.
What we know, though, is that home teams win more than two-thirds of all regular season games, so any recalculation that lifts Richmond's win at Kansas above Connecticut's lunch break vs. Sacred Heart is a good thing.
In the basic RPI this was true anyway. Connecticut's win over Sacred Heart hurt their RPI, even in winning. This is where schedule strength comes into play. What Lunardi ignored throughout the column is that the RPI is not the sole determinant of who gets an at-large bid. Richmond's win at Kansas was the top reason Richmond got an at-large bid, not because that's what the RPI said, but because human beings made the decision who gets in. The formula itself is a only tool.
By all reasonable consensus, Richmond was the final at-large team to be selected for the 2004 NCAA field. Those who were surprised by the Spiders' inclusion were overlooking their most glaring (and positive) credential; namely, an 8-7 road record against a very good road schedule.
Did I miss something? Why did UTEP and BYU get lower seeds than Richmond if the Spiders were the last team in? Why did Andy Katz report on Selection Sunday that the last decision was between UTEP and Utah State? Probably because UTEP was the last team in. While Richmond's status was uncertain over the last few weeks of the season, by Selection Sunday they were widely viewed as safe. You can't logically say that a 13 seed (UTEP) got in before an 11 seed (Richmond). This is one of a few exaggerations Lunardi makes to get across a point that has a weak foundation.
The weak foundation is the fact that the difference between the adjusted and basic RPIs are miniscule for the most part. Lunardi did a calculation involving a road win bonus multiplier of 1.25. In this case, road wins are worth 1.25 times as much as other wins. Nobody knows what the real multiplier is, but if the NCAA believes that road wins are twice as hard to attain, then the multiplier should be somehwere closer to 2. At any rate, Lunardi asserts that Richmond would have vaulted 10-12 spots up the RPI food chain under the new formula. The fault with this is that he only did the calculation for the Spiders. With a road bonus, everyone's RPI value will improve, assuming they won at least one road game. So I went ahead and recalculated RPI data for all teams, just to see how much Richmond actually improved. I boosted the multiplier to 1.5 for starters. The big movers for all teams ranked in the top 70...
Teams that were hurt 1) Rutgers -11 (56 to 67) 2) Michigan -5 (55 to 60) 3) St. Louis -4 (64 to 68) 4) Georgia -3 (48 to 51) 4) Nothern Iowa -3 (59 to 62)
The only team in this group that was remotely being considered for an at-large was Georgia. The reason they weren't selected was because of their abysmal road record. We didn't need a formula to confirm this. It's nice that Rutgers gets penalized the most, since they are widely viewed as underachieving road team. But I hope folks note the irony here. Your quality road win over Rutgers becomes a little less impressive under the adjusted RPI. Maybe this is how it should be, I'll let you decide.
Teams that were helped 1) Villanova +10 (67 to 57) 2) Pacific +6 (65 to 59) 3) Wisconsin Milwaukee +5 (75 to 70) 4) Washington +4 (56 to 52) 4) Colorado +4 (57 to 53)
The highest ranked team among the upward movers was Washington. Oh if only the committee had this new RPI, they wouldn't have missed them. Oh wait, they didn't miss them. The reason they were picked was related to their scorching recent play, both home and away. Richmond was a +3 from 47 to 44. Not the huge move that Lunardi predicted. Why is that? While Richmond's road record of 8-7 was slightly better than average, when compared to the better teams of college hoops, it's not exceptional.
I suppose I should explain why Villanova gets a big boost. It's difficult. It just goes to show how an alleged improvement can have unintended consequences. Villanova had only five road wins. However, the effect of the road bonus has more impact on teams with worse records, and Villanova had the worst record of teams in the top 70 at 15-15. Think about it, if a team has a perfect record, their winning percentage cannot be adjusted any higher no matter how many road wins they have. So the adjusted RPI will have some additional benefits to those big conference teams that have mediocre records.
By the way, I also tried a multiplier of 2 for road wins, and the result mainly involved more exaggerated changes for the teams listed above.
Notice that none of the big movers in either group were in the top 50 of the RPI, rendering the new system largely irrelevant. Add that to the fact that the committee has already shown that quality road wins are the most important aspect to the selection process for bubble teams, and it's unlikely they need any more numerical data in the selection process.
I don't want to be a wet blanket here. The adjusted RPI is a slight improvement on the basic version. In election parlance, the basic RPI is like calling a race on exit polls only. The adjusted RPI is like using exit polls and say, 5% of the actual vote. The adjusted RPI is a small improvement, but not enough to be worth the extra complexity - and flakiness - of the formula. It would have had no impact on last year's field. And no, Mike Brey, Notre Dame wouldn't have been a seven seed if this data were available last year.
P.S. I also want to point out that Lunardi/ESPN publishes his own "InsideRPI." This formula tries to replicate the secret adjustments that the NCAA uses. Notice that Richmond was 47th in the basic RPI I publish, while they dropped two spots in the InsideRPI. In other words, the adjustments the NCAA allegedly used made Richmond look worse. This is why I will more than likely stick to the basic RPI. The committee will still get the nitty gritty report with basic RPI data, and it's very close the adjusted version anyway.
One Step Closer
11.01.04
Exhibition season started tonight with seven D1 teams hitting the floor, the most notable of which were New Mexico, Louisiana Tech, and Santa Clara.
Oh Those Road Woes
The justification for adding a road-win bonus to the RPI is based on the premise that the home team wins 70% of college basketball games. This has been cited in nearly every article on the new RPI, and usually as a direct quote from basketball committee chairman Bob Bowlsby. This is a classic case of using stats in a misleading way. While that number is technically accurate, it is inaccurate to assume that all of those wins are due to a home-court advantage. For instance, in a large majority of non-conference games the home team also happens to be the better team, and in many cases the much better team. Did Illinois beat Maryland Eastern Shore because the game was played in Champaign?
One way to eliminate this effect is to limit the scope to conference games. This way ensures that the better team is equally at home and on the road in the sample. For all 2500+ conference games in the 2004-05 season, the home team won 62% of its games. But more to the point, let's find out how hard it is for teams being considered for an at-large bid.
Taking teams ranked 34 through 54 in last year's basic RPI, their difference in home and road winning percentage is striking. I chose this range because this includes teams generally considered on the bubble. It turned out in 2004, that 8 teams in this range got an at-large bid, 8 were left out, and the remaining 5 received automatic bids.
Overall these teams combined for a 89-84 (.514) record in conference road games. At home they were 135-38 (.780). It's interesting what happens when the at-large teams are separated from the NIT teams. The 8 at-larges went 39-27 (.591) on the road while the 8 NIT teams went 23-42(.354). Their respective home records were almost identical (51-15 vs. 47-18). Road play is clearly what separates the men from the boys. For these teams, it is not so hard to win on the road.
Of those 16 teams looking for an at-large bid in the slot I looked at, only two of the eight selected (Arizona and South Carolina) did not have a winning record in conference road games. Of the eight that were not picked, only Utah State had a winning road record in conference. Utah State was regarded as the last team left out of the field.
So it seems like a good idea to include site data in the RPI, except when you consider that the committee did a great job on its own of weeding out the folks that succeeded away from home. As I said last December:
The team that does the best job, year-in year-out, of abusing the home court advantage is Hawaii. It’s really no fault of theirs because they never have to schedule non-conference road games and they usually get some decent competition to come to the islands. This year they will have to head to the mainland to play in the Bracket Buster in February. But for the other 325 teams, the distribution of game locations doesn’t make enough difference to justify making a simple formula more complicated.
These posts were motivated by a discourse between Joe Lunardi and Jeff Sagarin last year in which Sagarin attempts to promote his own super-secret formula to replace the RPI. But college basketball does not need a super-secret formula - it hasn’t worked out real well for college football.
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.
Now that we know (sort-of) what the NCAA will do to adjust the RPI, just how much of a difference will it make? Was Notre Dame coach Mike Brey was right when he said,
"If we had that formula last year, we're a seven seed." [South Bend Tribune, 10/23/04]
Next Post: Last season's adjusted RPI.
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