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football prediction

You might not realize it but predicting a football game accurately is a very difficult thing. Take a look at a plot of the line against the actual result from the NFL games this past season. Basically, the results is going to end up being the line plus/minus about 24 points.

line vs actual outcome nfl 2014

basketball results

I’ve made an improvement to the NCAA basketball results. The tables are now sortable by any of the columns. I will probably do the same with the NBA. Eventually it might also be nice to add a link to a daily updated plot of the results. They seem to give you an idea if any system is on a hot streak.

year to date NCAA basketball predictions performance

Given time I may try to start putting up some graphics. Here are how well the various rating systems have done through the course of the season to date in college basketball. I know it is kind of messy.

update: I increased the resolution of both these and the NFL plots below. You can right click them to pull them up full screen.

winning percentage over time

Against the spread over the season to date

Mean square error across the season to date

Bias across the season to date

Plots of NFL results over time

NFL systems Straight Up.

NFL system  winning percentage over time

NFL systems Against the Spread

NFL system ATS over time

NFL systems Absolute Error

NFL system absolute error over time

NFL systems Mean Square Error

NFL system MSEover time

NFL systems average Bias

NFL system average bias over time

Best NFL Systems

I get asked quite often which is the best system? Who should I follow, etc.
My typical response is that I don’t really believe there is any best system. There is something about the landscape each season that makes each season unique. Very few systems, if any, are at the top every year. I now have 15 years worth of results and I have tried to determine a way to say who are the best. To do this I decided to judge based only on second half results. A system needed to have made at least 100 predictions in the second half to qualify. Like I mentioned before, every season is different. So I didn’t want to just calculate the best overall winning percentage. Some seasons all numbers are high and other seasons all numbers are lower. In looking for something that I could compare relative performance year to year I decided to base these results on average percentile ranking. So if you were the best every year you would have a score of 1, the worst every year would be a score of 100.
I think I will only list those that are still making predictions.

Best ratings for straight up winners
1. Kenneth Massey (avg percentile 26.6. So note on average nobody is even in the top quarter every year!)
2. Computer Adjusted line/Updated Line/opening line (just rolling these all into one)
3. Game Time Decison
4. Beck Elo
5. Sonny Moore

Keep an eye on these, they could have been on the above list if they had more seasons:
Ironrank.com, Pi-Ratings, Lou St. John
And two good ones that are no longer around: Eric Hollobaugh and JFM Power Ratings

Best against the spread
1. Nutshell Retro (avg percentile 29.6)
2. Game Time Decison
3. Statfox
4. Sagarin overall rating
5. Roger Johnson

Systems to keep an eye on: Turnover adjusted Least squares, Ironrank.com

Best at coming closest to the actual win margin
1. Computer Adjusted line/Updated Line/opening line (average percentile 9.0)
2. Game Time Decision
3. System Average or Median
4. Kenneth Massey
5. Dokter Entropy

Keep an eye on these, Ironrank.com
Good but no longer around: Jeff Self, Hank Trexler

The accuracy numbers, absolute error and square error, do have certain systems that are typically closer to the top. But for either picking games straight up or against the spread there really is no always good system. The truth is that there is a huge margin of error on these things which means for the most part every system is within another systems’s margin of error. If a game, like tomorrow’s Superbowl, is a pick’em, then a 95% confidence interval on what the actual outcome will end up being is something like either team will win by 24 points or less.

NFL play by play data

I have never looked at NFL play by play data and am considering starting a new project to look at it. Does anybody know the best source for this data? I found Brian Burke’s data. Is there anything else, more recent and maybe with more info? Anybody know? Leave a comment.

NFL Divisional Playoffs

  home           p(win)   p(cover)   road            p(win)   p(cover)   line   lineavg

  Green Bay     0.59256    0.43811   Dallas         0.40744    0.56189    7.0    4.2221
  Denver        0.63827    0.46731   Indianapolis   0.36173    0.53269    8.0    6.5460
  Seattle       0.73402    0.51969   Carolina       0.26598    0.48031   12.0   12.8822
  New England   0.65145    0.49735   Baltimore      0.34855    0.50265    7.5    7.3808

NFL Wildcard playoffs

If the BCS was still being used the championship game would have been Alabama vs Florida St. With Alabama most likely winning easy and continuing the SEC overhype. I think now we know that all those BCS years the champ was still the ‘mythical’ national champion.

Last week the top 3 NFL picks went 3-0 to finish the regular season 30-18, 62.5. Last season the top 3 were 29-18-1. So two very similar seasons back to back. The top game of the week was 10-6, also 62.5%.
So why are you paying for a service and still getting a losing record?
Interestingly two years ago the top 3 NFL games were only 14-28. Which is about what happened with the NCAA numbers this season.
Only one of the games is worth considering this week, Arizona at Carolina playing again with their third string qb.

 home            p(win)   p(cover)      road       p(win)   p(cover)   line    lineavg

  Carolina       0.47526    0.32776   Arizona      0.52474    0.67224    7.5   -1.11671
  Indianapolis   0.60211    0.53952   Cincinnati   0.39789    0.46048    3.0    4.80465
  Dallas         0.63076    0.47145   Detroit      0.36924    0.52855    7.5    6.21634
  Pittsburgh     0.55781    0.49184   Baltimore    0.44219    0.50816    3.0    2.63254

NFL week 17

The top 3 NFL picks have been consistently getting 2 out of 3 correct. The top game is 9-6, the top 3 are 27-18.
Be aware that that week the top two games are picking teams playing their 3rd string quarterbacks.

home             p(win)   p(cover)   road            p(win)   p(cover)    line    lineavg

San Francisco   0.49136    0.33912   Arizona        0.50864    0.66088     7.5    -0.3868
Baltimore       0.68905    0.39458   Cleveland      0.31095    0.60542    14.5     9.6077
Washington      0.32669    0.39938   Dallas         0.67331    0.60062    -4.0    -8.6984
New England     0.69718    0.57052   Buffalo        0.30282    0.42948     7.0    10.2317
Kansas City     0.58543    0.56412   San Diego      0.41457    0.43588     1.0     3.8825
Tennessee       0.28948    0.43899   Indianapolis   0.71052    0.56101    -8.5   -11.3231
Houston         0.72578    0.56042   Jacksonville   0.27422    0.43958     9.5    12.2395
Miami           0.68528    0.55274   N.Y. Jets      0.31472    0.44726     7.0     9.3845
Green Bay       0.64259    0.45142   Detroit        0.35741    0.54858     9.0     6.8178
N.Y. Giants     0.47360    0.45147   Philadelphia   0.52640    0.54853     1.0    -1.1790
Atlanta         0.59758    0.54455   Carolina       0.40242    0.45545     2.5     4.5055
Seattle         0.72498    0.48390   St. Louis      0.27502    0.51610    13.0    12.2725
Tampa Bay       0.42778    0.51590   New Orleans    0.57222    0.48410    -4.0    -3.2880
Pittsburgh      0.56425    0.48649   Cincinnati     0.43575    0.51351     3.5     2.8985
Denver          0.76674    0.51061   Oakland        0.23326    0.48939    15.5    15.9797
Minnesota       0.64332    0.49735   Chicago        0.35668    0.50265     7.0     6.8813

Bowl games

The regular season didn’t go so well so not sure I would trust these either.

home                  p(win)  p(cover)  road            p(win)  p(cover)   line   lineavg

Alabama              0.57766   0.38654  Ohio St.       0.42234   0.61346   10.0    4.0067
Kansas St.           0.56155   0.58990  UCLA           0.43845   0.41010   -1.5    3.1128
Louisiana-Lafayette  0.43583   0.41763  Nevada         0.56417   0.58237    1.0   -3.3877
South Carolina       0.49100   0.56977  Miami (Fla.)   0.50900   0.43023   -4.0   -0.4505
Auburn               0.57192   0.43662  Wisconsin      0.42808   0.56338    7.0    3.7278
Western Kentucky     0.61703   0.56156  Central Mich.  0.38297   0.43844    3.0    6.1036
Texas A&M            0.49164   0.56053  West Va.       0.50836   0.43947   -3.5   -0.4201
Air Force            0.53581   0.55538  Western Mich.  0.46419   0.44462   -1.0    1.7992
Cincinnati           0.50463   0.44602  Virginia Tech  0.49537   0.55398    3.0    0.2350
USC                  0.58207   0.44645  Nebraska       0.41793   0.55355    7.0    4.2579
Mississippi St.      0.59965   0.45586  Georgia Tech   0.40035   0.54414    7.5    5.2407
Rice                 0.49835   0.45900  Fresno St.     0.50165   0.54100    2.0   -0.0835
LSU                  0.66941   0.54038  Notre Dame     0.33059   0.45962    7.5    9.5736
Oregon               0.64144   0.46071  Florida St.    0.35856   0.53929   10.0    7.9328
Georgia              0.66025   0.53581  Louisville     0.33975   0.46419    7.0    8.8066
Stanford             0.70421   0.46647  Maryland       0.29579   0.53353   14.0   12.2639
North Carolina       0.52664   0.46676  Rutgers        0.47336   0.53324    3.0    1.3337
San Diego St.        0.51761   0.46759  Navy           0.48239   0.53241    2.5    0.8787
Arkansas St.         0.45857   0.52760  Toledo         0.54143   0.47240   -3.5   -2.1034
Houston              0.41709   0.47533  Pittsburgh     0.58291   0.52467   -3.0   -4.2337
Baylor               0.52596   0.47561  Michigan St.   0.47404   0.52439    2.5    1.2893
Arkansas             0.63101   0.52083  Texas          0.36899   0.47917    6.0    7.0596
Boston College       0.56710   0.51735  Penn St.       0.43290   0.48265    2.5    3.3558
Tennessee            0.55491   0.48535  Iowa           0.44509   0.51465    3.5    2.7681
Bowling Green        0.46461   0.51409  South Alabama  0.53539   0.48591   -2.5   -1.7899
Florida              0.64773   0.51386  East Carolina  0.35227   0.48614    7.5    8.2150
TCU                  0.57115   0.51357  Mississippi    0.42885   0.48643    3.0    3.6929
Washington           0.59421   0.48734  Oklahoma St.   0.40579   0.51266    5.5    4.8650
Oklahoma             0.56827   0.50989  Clemson        0.43173   0.49011    3.0    3.4992
Louisiana Tech       0.61612   0.50938  Illinois       0.38388   0.49062    6.0    6.5019
Marshall             0.66703   0.49186  Northern Ill.  0.33297   0.50814   10.0    9.5770
Central Florida      0.54483   0.49550  NC St.         0.45517   0.50450    2.5    2.2733
Utah St.             0.68143   0.50414  UTEP           0.31857   0.49586   10.0   10.2070
Arizona              0.56281   0.50397  Boise St.      0.43719   0.49603    3.0    3.1999
Memphis              0.53636   0.49652  BYU            0.46364   0.50348    2.0    1.8262
Arizona St.          0.64021   0.49869  Duke           0.35979   0.50131    7.5    7.4349
Missouri             0.59650   0.49877  Minnesota      0.40350   0.50123    5.0    4.9390
Colorado St.         0.44165   0.50058  Utah           0.55835   0.49942   -3.0   -2.9706