Random Walker Rankings for NCAA Football




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2007 Random Walker Bowl Game Predictions

December 20th, 2007

The bowl games start tonight, and we've had multiple requests for information about how one might use rankings like these to predict future outcomes and to order the confidence in those picks. For instance, part of playing ESPN's College Bowl Mania (not endorsing it, just using it as an example), involves ranking your 32 picks in order of confidence. We definitely don't want to start a whole discussion here about predictive versus retrodictive rankings; but we do want to remind you of the main philosophy of the Random Walker Rankings: These rankings are not intended to be "best" in any sense; rather, they are an example of a ranking system that is both simple-to-describe and demonstrably valuable. There are more complicated systems out there that one should probably rely on to give better predictions than those here. But the random walkers do suggest some things about the probable outcomes of the upcoming bowl games.

Details you may not care about: The claim being leveraged here is that one should be able to calculate the probability of upcoming game outcomes from an assumption that the information already obtained is good. Specifically, if we add a single upcoming game as a fractional outcome to the existing ranking information in such a way as to not alter that information, then those fractional outcomes represent a probability prediction for the upcoming game. That is, if the fraction that doesn't alter the existing rankings is a w% win for the first team and (1-w)% for the second team, then we would say the first team has a w% chance of winning the game. This is a wonderfully general principle. It is also fabulously erroneous! There are too many problems with this to enumerate here, but as a brief example, an attempt to use this principle to predict last weekend's NFL games suggested that New England had a 120% chance of beating the NY Jets (yes, a little linear programming might help here; but there are other problems too).

With all the caveats out of the way, we present to you the RWFL predictions at p=0.75 for the 2007 bowl games (in this particular case, we calculated the rankings over the full connected component of college football without collapsing non-FBS teams into a single node, using all game outcomes through December 15th). Each game selection is specified by taking the higher-ranked team to beat the lower-ranked team. The games are presented in order of confidence (highest to lowest), as specified by the mean of the stated probability spread (obtained individually by the first-place votes and the last-place votes).

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Papajohns.com Bowl (Dec. 22, 1 p.m.  ESPN2 HD)                     
Cincinnati (9-3) over Southern Miss (7-5)
81-93%
----
Champs Sports (Dec. 28, 5 p.m.  ESPN HD)                           
Boston College (10-3) over Michigan St (7-5)
78-81%
----
AT&T Cotton (Jan. 1, 2008, 11:30 a.m.  FOX)                        
Missouri (11-2) over Arkansas (8-4)
71-76%
----
Konica Minolta Gator (Jan. 1, 2008, 1 p.m.  CBS)                   
Virginia (9-3) over Texas Tech (8-4)
68-73%
----
New Mexico (Dec. 22, 4:30 p.m.  ESPN HD)                           
New Mexico (8-4) over Nevada (6-6)
62-79%
----
Allstate Sugar (Jan. 1, 2008, 8:30 p.m.  FOX)                      
Georgia (10-2) over Hawai`i (12-0)
67-74%
----
Pacific Life Holiday (Dec. 27, 8 p.m.  ESPN HD)                    
Arizona St (10-2) over Texas (9-3)
69-69%
----
R+L Carriers New Orleans Bowl (Dec. 21, 8 p.m.  ESPN2 HD)          
Florida Atlantic (7-5) over Memphis (7-5)
67-69%
----
International (Jan. 5, 2008, Noon  ESPN2 HD)                       
Rutgers (7-5) over Ball St (7-5)
63-70%
----
Pioneer Las Vegas (Dec. 22, 8 p.m.  ESPN HD)                       
Brigham Young (10-2) over UCLA (6-6)
62-69%
----
Capital One (Jan. 1, 2008, 1 p.m.  ABC HD)                         
Florida (9-3) over Michigan (8-4)
64-66%
----
FedEx Orange (Jan. 3, 2008, 8 p.m.  FOX)                           
Virginia Tech (11-2) over Kansas (11-1)
62-67%
----
Roady's Humanitarian (Dec. 31, 2 p.m.  ESPN2)                      
Georgia Tech (7-5) over Fresno St (8-4)
63-65%
----
Texas (Dec. 28, 8 p.m.  NFL Network)                               
TCU (7-5) over Houston (8-4)
62-66%
----
Chick-fil-A (Dec. 31, 7:30 p.m.  ESPN HD)                          
Clemson (9-3) over Auburn (8-4)
58-69%
----
Sheraton Hawaii (Dec. 23, 8 p.m.  ESPN)                            
Boise St (10-2) over East Carolina (7-5)
62-65%
----
Emerald (Dec. 28, 8:30 p.m.  ESPN HD)                              
Oregon St (8-4) over Maryland (6-6)
57-64%
----
Insight (Dec. 31, 6 p.m.  NFL Network)                             
Oklahoma St (6-6) over Indiana (7-5)
58-62%
----
Rose Bowl presented by Citi (Jan. 1, 2008, 4:30 p.m.  ABC HD)      
Southern Cal (10-2) over Illinois (9-3)
55-62%
----
Motor City (Dec. 26, 7:30 p.m.  ESPN HD)                           
Purdue (7-5) over Central Michigan (8-5)
57-60%
----
Outback (Jan. 1, 2008, 11 a.m.  ESPN HD)                           
Tennessee (9-4) over Wisconsin (9-3)
55-60%
----
San Diego County Credit Union Poinsettia (Dec. 20, 9 p.m.  ESPN HD)
Utah (8-4) over Navy (8-4)
52-62%
----
Bell Helicopter Armed Forces (Dec. 31, 12:30 p.m.  ESPN)           
Air Force (9-3) over California (6-6)
50-61%
----
Brut Sun (Dec. 31, 2 p.m.  CBS)                                    
South Florida (9-3) over Oregon (8-4)
53-58%
----
GMAC (Jan. 6, 2008, 8 p.m.  ESPN HD)                               
Tulsa (9-4) over Bowling Green (8-4)
47-63%
----
Allstate BCS Championship Game (Jan. 7, 2008, 8 p.m.  FOX)         
LSU (11-2) over Ohio State (11-1)
52-57%
----
Valero Alamo (Dec. 29, 8 p.m.  ESPN HD)                            
Penn State (8-4) over Texas A&M (7-5)
52-57%
----
Gaylord Hotels Music City (Dec. 31, 4 p.m.  ESPN HD)               
Kentucky (7-5) over Florida St (7-5)
49-52%
----
Meineke Car Care (Dec. 29, 1 p.m.  ESPN HD)                        
Connecticut (9-3) over Wake Forest (8-4)
47-54%
----
AutoZone Liberty (Dec. 29, 4:30 p.m.  ESPN HD)                     
Mississippi St (7-5) over Central Florida (10-3)
49-51%
----
PetroSun Independence (Dec. 30, 8 p.m.  ESPN HD)                   
Alabama (6-6) over Colorado (6-6)
49-50%
----
Tostitos Fiesta (Jan. 2, 2008, 8 p.m.  FOX)                        
Oklahoma (11-2) over West Virginia (10-2)
43-54%
----

There are some interesting wrinkles in the above, in that the last three cases (least confident) have the middle of the probability range of the higher-ranked team beating the lower-ranked team below 50%. There are 3 other cases where the specified range also encloses 50%, so these picks are obviously not very confident! Do with the above as you will, we merely provide it for fun...


GT UNC Copyright © 2007 Peter J. Mucha (mucha@unc.edu), Thomas Callaghan, Mason A. Porter

THIS PAGE IS NEITHER A PUBLICATION OF THE UNIVERSITY OF NORTH CAROLINA (UNC) NOR THE GEORGIA INSTITUTE OF TECHNOLOGY (GT), WHERE THIS WORK BEGAN. NEITHER UNC NOR GT ARE RESPONSIBLE FOR EDITING OR EXAMINING ITS CONTENT. THE AUTHOR OF THIS PAGE IS SOLELY RESPONSIBLE FOR THE CONTENT. THE RIGHTS TO ANY AND ALL MATERIALS CREATED BY THE AUTHOR OF THIS PAGE ARE RETAINED BY THAT AUTHOR.