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Posted by Huckleberry on January 8th, 2009 under Football
Many ratings systems are based on the idea that a sports team’s (or athlete’s) performance is normally distributed about their true strength. This true strength is estimated, then, to be the mean of the normal distribution and is what the system will spit out as the team’s final rating. This idea that a team has a true strength around which their performances are normally distributed is both logical and convenient for the computers.
The question is raised, though, about the standard deviation of performances. A consistent athlete or team should show a low standard deviation in their performances while an inconsistent team, of course, should have a high standard deviation. As usual, I will begin by issuing a few warnings regarding the information I’m going to present. In order to calculate a team’s standard deviation (or consistency), you have to assume that their opponent in each game was playing at its mean. With the limited number of data points in a college football season, it seems entirely possible that a team may be fortunate enough to catch more teams on bad days than good days or vice versa, and to do so in a high enough percentage to affect their consistency rating. And that warning includes what should always be considered when dealing with statistical analysis of college football – there aren’t enough data points to be completely sure about most things we care about. Sure there’s enough data to tell me that Florida should practically never lose to North Texas, but delineations between teams of similar strength don’t come with a great amount of confidence in this sport. (Playoff, anyone?)
I calculated each team’s consistency rating based on their power score for each game played. This power score can essentially be viewed to be the margin of victory in each game compared to the margin of victory an average opponent playing an average game would have against that opponent when the opponent played an average game. That’s a lot of average; I almost feel like I’m discussing Texas A&M recruiting. For this analysis I focused only on Division 1A teams and matchups.
| Most Consistent Teams | ||
|---|---|---|
| Rank | Team | SDEV |
| 1 | Texas A&M | 8.35 |
| 2 | Air Force | 8.50 |
| 3 | Georgia | 8.71 |
| 4 | Miami (FL) | 9.11 |
| 5 | TCU | 9.29 |
| 6 | Akron | 9.38 |
| 7 | Virginia Tech | 9.39 |
| 8 | Boston College | 9.57 |
| 9 | Nebraska | 9.71 |
| 10 | Syracuse | 9.72 |
| Least Consistent Teams | ||
|---|---|---|
| Rank | Team | SDEV |
| 1 | Tulsa | 23.39 |
| 2 | San Diego St. | 20.49 |
| 3 | New Mexico | 19.86 |
| 4 | Rutgers | 19.07 |
| 5 | UTEP | 18.68 |
| 6 | Maryland | 18.42 |
| 7 | North Carolina St. | 18.10 |
| 8 | Virginia | 18.08 |
| 9 | Texas Tech | 18.06 |
| 10 | Missouri | 17.82 |
| Top 10 Power Teams w/ Consistency | ||||
|---|---|---|---|---|
| Rank | Team | Power | SDEV | Cons Rk |
| 1 | Florida | 63.67 | 12.25 | 46 |
| 2 | Oklahoma | 62.63 | 14.37 | 86 |
| 3 | Southern Cal | 60.19 | 12.99 | 62 |
| 4 | Texas | 57.20 | 10.33 | 20 |
| 5 | Penn St. | 53.47 | 11.14 | 31 |
| 6 | Texas Tech | 47.40 | 18.06 | 112 |
| 7 | TCU | 46.23 | 9.26 | 5 |
| 8 | Missouri | 45.82 | 17.82 | 111 |
| 9 | Ohio St. | 45.60 | 13.44 | 70 |
| 10 | Utah | 45.11 | 11.92 | 40 |
A few items about the tables:
Pros and Cons
Normally when people discuss college football teams, everyone talks about wanting to be a consistent football team. What they mean, or should mean, is that they want to be a consistently good football team. When you consider the problem of maximizing your team’s wins during the season, if you are a good football team whose opponents are all or nearly all worse than your team (the mean of the distribution) then you will want to be extremely consistent. This is because upsets are more probable when an inconsistent team is involved. By the same token, if you are a bad football team that will be playing mostly opponents that are better than your team, then consistency isn’t really something you should strive for if you want to win the most games possible. A team that is bad and plays at a consistent level will not get up for an upset. A team that is bad and plays inconsistently might put out a real stinker, but they are also more likely to upset a better team.
Take Texas A&M for example. They were a bad football team this year, but their performances were the most consistent in the nation. If we know that the Aggies are team whose performances averaged out to their power rating of 19.48, doesn’t it make sense that they would rather play half their games at a 34.48 level and half at a 4.48 level instead of all at their average strength? When playing games against a schedule that averaged 35.45 in terms of power ratings, a team with a 19.48 rating will win more games by being inconsistent than by being a consistent squad. The bottom line is that if you’re going to suck, you want to do it erratically.
On the other hand, there’s Texas Tech. A team with a relatively high power rating will want to play consistently against lower-rated teams. I won’t elaborate here as the reasons should be obvious. However, it should be noted that a team’s power rating is less important to whether or not they should be consistent than their schedule. Tech, while #6 in the power ratings, actually played two teams with higher ratings. Being inconsistent helps against those two teams as far as increasing the expected value in terms of wins. And in reality, that’s what happened with the Red Raiders this year. With no standard deviation, they would have been expected to lose to both Texas and Oklahoma by comfortable margins. Instead they upset Texas in a close game and got destroyed by Oklahoma due to inconsistency (at least partially known as the Lubbock factor in Tech’s case).
Expected Wins in a True Round Robin
My power ratings only display the mean of a team’s distribution. Taking the distribution of all the team’s power ratings, then, and normalizing each team’s specific rating enabled us to give a percentage chance that one team would beat another. This method, though, did not account for the consistency of each team and we’ve shown that this will have an effect. Now that we have identified each team’s rating as a normal distribution of its own we can recalculate that percentage in each case thanks to the property of the sum of normally distributed variables.
Furthermore, thanks to my favorite toy, Excel, we can simulate a complete round robin of Division 1A football using this calculation. There are many things we can look at after doing this, including seeing how changing a specific team’s consistency changes their expected win total out of the 119 matchups. We can also compare a team’s rank in expected wins to their rank in power rating. We would expect that highly rated teams with poor consistency would fall in the rankings and that lowly rated teams with poor consistency would rise.
So let’s begin with the Aggies and Red Raiders. In a full round robin, based on their current rating and standard deviation, Texas A&M’s expected value in wins would be about 45.5 according to this calculation while the Red Raiders would have an EV of 94.6 wins. If we simply switch their standard deviation values, the Aggies EV goes up to 48.2 wins while the Red Raiders’ goes up to 101.0 wins. This makes sense based on the theory that consistency helps a good team’s expected wins and hurts a bad team’s expected wins.
Below is a table of the Top 25 in the power ratings along with their power rating, power rating rank, expected winning percentage in a true round robin, and their expected winning percentage rank. Thankfully it just so happened that nobody went into or out of the Top 25.
| Rank | Team | Power | SDEV | Rk | EWP | EWPRk |
|---|---|---|---|---|---|---|
| 1 | Florida | 63.67 | 12.25 | 46 | 0.952 | 1 |
| 2 | Oklahoma | 62.63 | 14.37 | 86 | 0.938 | 2 |
| 3 | Southern Cal | 60.19 | 12.99 | 62 | 0.931 | 3 |
| 4 | Texas | 57.20 | 10.33 | 20 | 0.925 | 4 |
| 5 | Penn State | 53.47 | 11.14 | 31 | 0.894 | 5 |
| 6 | Texas Tech | 47.40 | 18.06 | 112 | 0.795 | 10 |
| 7 | TCU | 46.23 | 9.29 | 5 | 0.832 | 6 |
| 8 | Missouri | 45.82 | 17.82 | 111 | 0.779 | 13 |
| 9 | Ohio State | 45.60 | 13.44 | 70 | 0.802 | 8 |
| 10 | Utah | 45.11 | 11.92 | 40 | 0.805 | 7 |
| 11 | Alabama | 44.81 | 12.45 | 48 | 0.798 | 9 |
| 12 | Oregon | 44.34 | 12.63 | 52 | 0.792 | 11 |
| 13 | Mississippi | 43.96 | 15.26 | 93 | 0.772 | 15 |
| 14 | Iowa | 43.33 | 15.68 | 97 | 0.762 | 17 |
| 15 | Boise St | 43.17 | 11.03 | 29 | 0.785 | 12 |
| 16 | Oklahoma St | 43.00 | 13.98 | 79 | 0.767 | 16 |
| 17 | California | 42.58 | 11.81 | 37 | 0.773 | 14 |
| 18 | Arizona | 41.14 | 12.56 | 51 | 0.750 | 18 |
| 19 | Florida St | 40.28 | 12.00 | 41 | 0.741 | 19 |
| 20 | Oregon St | 40.12 | 14.08 | 83 | 0.728 | 21 |
| 21 | Georgia | 39.21 | 8.71 | 3 | 0.740 | 20 |
| 22 | North Carolina | 37.34 | 17.73 | 109 | 0.672 | 24 |
| 23 | Nebraska | 36.80 | 9.71 | 9 | 0.698 | 22 |
| 24 | Kansas | 35.74 | 14.01 | 81 | 0.664 | 25 |
| 25 | Clemson | 35.26 | 9.77 | 11 | 0.673 | 23 |
According to this model, Florida is a little over a one-point favorite tonight, has a 52.2% chance of winning, and has a 39.6% chance of covering the current 6-point line.
2009 BCS Championship Game, College Football, Computer Ratings
Trips Right commented on the blog post Did Rick Barnes use a plant last night to distract KU players? ago
Wholesome goodness. Thanks for posting.
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Ag_in_TX wrote a new blog post: Did Rick Barnes use a plant last night to distract KU players? 2 minutes ago
If you watched the game, and if you have one drop of testosterone in your bloodstream, you couldn’t have missed her. The redhead with huge tracts of land – right behind the KU bench – who stood for every time out and stared at the KU players.
She stuck out like a sore thumb. Never
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Darius Pourceau commented on the blog post Recruiting the Trenches 4 minutes ago
Welcome to the site guys! Aaron Rodgers is the man.
http://bornhogwild.fantake.com/
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Art Vandelay commented on the blog post Texas Hoops vs. Kansas: Post-Mortem 6 minutes ago
Bob, essentially what you are saying is that we are not a well coached basketball team. I agree.
Jordan Hamilton is a selfish and lazy player. He is a terrible fit to play for Barnes. Not sure if either one will be around next season at this rate.
We went scoreless for 10:54 during
Trips Right commented on the blog post 2011 Texas Football Recruiting 17 minutes ago
Well done. The Barney Frank line blindsided me like a strain of juarez clap. Funny stuff.
I’d like for us to go out of state for a QB and at least 1 maybe two CB’s. Is Quandre tall enough to play corner or angry enough to play safety?
Rumor around the campfire is
skymonkeyhorn commented on the blog post Texas Hoops vs. Kansas: Post-Mortem 29 minutes ago
I feel our pain…
Was Barnes wearing a helmet last night. I did not notice as I was in awe of the blood being spilled
on the floor for almost 11 minutes without a point.
Coach Knight was reading this blogs out loud for TV.
The most insightful was that Barnes needs to go to the 7-8
James commented on the blog post 2011 Texas Football Recruiting 32 minutes ago
Barney Frank and Mormon quips in the same post. My Tuesday is complete.
Texas HS football is going through a phase (era?) where the best athlete talent is being put on offense. DBs aren’t being developed in vast quantities. Why wouldn’t you go after a couple OOS DBs?
Trips Right commented on the blog post Texas Hoops vs. Kansas: Post-Mortem 34 minutes ago
ponderos, shouldn’t you be supersizing something somewhere?
Trips Right commented on the blog post Texas Hoops vs. Kansas: Post-Mortem 36 minutes ago
Gillispie’s a mid-major clown because of his off the court indiscretions. Seriously, The University of Texas is much too high profile to risk its brand and image with this moron. And anyone that mentions Augie Garrido should be permabanned the intertubes. The situations aren’t remotely similar.
If you want to go down the
Trips Right commented on the blog post Texas Hoops vs. Kansas: Post-Mortem 42 minutes ago
Leonidas, none of those points came against Dex. Boxscores aren’t reality, they’re like porn movies. If porn was real everyone would be a plummer.
As for Pittman on offense, Aldrich wasn’t playing him straight up, he was getting a double virtually everytime down. That’s not Aldrich’s fault but it’s reality.
Pittman rarely
Mister Mike commented on the blog post Nebraska Fits the Profile of the 2010 National Champion 48 minutes ago
Good line. What is the thinking on his ability vs. the injury?
It’s funny you should ask. I’m working on putting something together right now that will be discussing this very topic. I know you’re waiting with bated breath for it too. Admit it.
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Bob in Houston commented on the blog post Texas Hoops vs. Kansas: Post-Mortem 1 hour, 10 minutes ago
Should be “complementary” scorers. Oh well.
Bob in Houston commented on the blog post Texas Hoops vs. Kansas: Post-Mortem 1 hour, 14 minutes ago
OK, I was there. Not the best seat in the house, but not a bad one either.
Trips hit part of what struck me over and over. KU had offensive options/outlets when Texas forced them into trouble (which happened quite a bit, as the stats showed that Texas did bring defense last night), and the
Mister Mike wrote a new blog post: ”Bo Made Me Cry.” 1 hour, 53 minutes ago
At least, that’s the line I would expect to hear from Rivals or Scouts if they were in a relationship with Bo Pelini and ended up going to Dr. Phil to try and work out their differences. Of course, that would never happen because Bo would’ve just laughed, packed her shit up, and thrown it
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HenryJames commented on the blog post Scholarship Numbers & Junior Days 2 hours, 5 minutes ago
CTJ,
Rivals doesn’t think there are any elite players in Texas this year. Do you think we’ll have to go out of state to compensate?
Thanks!
D W commented on the blog post Another night, another would-be hero 2 hours, 57 minutes ago
Hamilton is so stupid on the court it makes my teeth hurt.
Sailor Ripley commented on the blog post Top 8 Teams in College Hoops 5 hours, 49 minutes ago
Yeah, I think we can scratch Texas out of there. Who takes place 8?
Sailor Ripley commented on the blog post Looking at Texas 6 hours, 2 minutes ago
You guys have a basketball team. Is it Indianapolis this year?
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Scipio Tex wrote a new blog post: 2011 Texas Football Recruiting 6 hours, 8 minutes ago
Junior Days are right around the corner, so I thought we’d break down needs, talk recruits, and find a ray of gridiron sunshine in the long and cursed offseason.
CTJ gives us his thoughts too. Had I realized, I might have saved myself the typing.
Unlike last year where DFW held an
admin commented on the blog post Making a Case for a 1 Seed: Villanova Tops the ’Neers 6 hours, 22 minutes ago
Enjoyed watching these guys tonight. I was blown away to see Huggy was 5X coach of the year. He seems like a tourney flame out more often than not. That Kenyon Marting leg break didn’t do him any favors.
How do you see them progresing in the tourney?
admin commented on the blog post Making a Case for a 1 Seed: Villanova Tops the ’Neers 6 hours, 22 minutes ago
Enjoyed watching these guys tonight. I was blown away to see Huggy was 5X coach of the year. He seems like a tourney flame out more often than not. That Kenyon Martin leg break didn’t do him any favors.
How do you see them progresing in the tourney?
admin commented on the blog post Duke Basketball: The Devil You Know? 6 hours, 23 minutes ago
Avery Bradley, who shot 77% from the foul line in high school and is now shooting 47% at Texas would probably be shooting closer to his high school average if he played at Duke.
Sweet Jesus that’s ridonkulous.
admin commented on the blog post Duke Basketball: The Devil You Know? 6 hours, 23 minutes ago
Avery Bradley, who shot 77% from the foul line in high school and is now shooting 47% at Texas would probably be shooting closer to his high school average if he played at Duke.
Sweet Jesus that’s ridonkulous.
Jeff Julian wrote a new blog post: Recruiting the Trenches 6 hours, 59 minutes ago
Importance of Recruiting Rankings by Position.
Now that the recruiting season is over and most Cal fans are waxing poetic (along with some Texas fans) about how great these 17-18 year olds will be, I thought it might be interesting to take a look at recruiting rankings as a potential measurement for future success.
For the purposes
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admin wrote a new blog post: Welcome 7 hours, 4 minutes ago
HenryJames will soon be here to captivate you with his wit and extensive knowledge of the most storied franchise in professional sports history, the New York Yankees.
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admin commented on the blog post Nebraska Fits the Profile of the 2010 National Champion 7 hours, 16 minutes ago
Interesting but call me skeptical now. We’ve got experience at QB but not positive experience.
Good line. What is the thinking on his ability vs. the injury?
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admin commented on the blog post Nebraska Fits the Profile of the 2010 National Champion 7 hours, 16 minutes ago
Interesting but call me skeptical now. We’ve got experience at QB but not positive experience.
Good line. What is the thinking on his ability vs. the injury?
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bigdukesix commented on the blog post Scholarship Numbers & Junior Days 7 hours, 28 minutes ago
I really don’t want to repeat the horrid situation of the past few years where we starved for depth and talent at DT. It’s critical not to let defensive line recruiting slip. That said, if we bring in two tackles and two ends this year that would be 21 scholarships used on the
Arthur Goddamn Fenstemaker commented on the blog post Weekly Stats Update 7 hours, 30 minutes ago
bigdukesix commented on the blog post Scholarship Numbers & Junior Days 7 hours, 36 minutes ago
It appears as though the dude is committed to raiding the SEC and ignoring the West Coast.
It’s understandable, with the way that recruiting is generally territory based. Isaiah Crowell, the RB we’ve been linked to, goes to Columbus Carver. That’s an Auburn pipeline school. Still, I can’t imagine that recruitment lasting much
© 2009 Fantake. All rights reserved unless otherwise indicated.
Thornton Melon said:
January 8th, 2009 at 1:55 pm
I feel like I just gave birth… to an accountant!
dasmithjones said:
January 8th, 2009 at 2:03 pm
Okay dude!
t1climb1 said:
January 8th, 2009 at 2:12 pm
I’m too stupid to talk to you Huck.
Brian Combs said:
January 8th, 2009 at 2:19 pm
Just for fun, what happens if you extend it out multiple years?
Huckleberry said:
January 8th, 2009 at 2:20 pm
I’m too stupid to talk to you Huck.
I doubt that. I’ve talked to HenryJames before.
beowulf said:
January 8th, 2009 at 2:21 pm
Dude.
Huckleberry said:
January 8th, 2009 at 2:22 pm
I’m interested in performing the analysis on other seasons, but scoring environment changes might make combining seasons difficult. I haven’t looked at it that closely yet.
One of the reasons I want to run last year is to run a sanity check using Oregon. They should have a higher than average standard deviation because of Dixon’s injury.
Brian Combs said:
January 8th, 2009 at 2:29 pm
Using data from the previous season or two (addressing the reduced confidence in some way) might improve the data set. Yes, teams do sometimes have major differences from one season to the next, but in most cases I expect it would look more like a trend line.
Disclaimer: We’re well beyond my statistical knowledge here. Stats 301 was an awful long time ago.
HenryJames said:
January 8th, 2009 at 4:37 pm
What a fascinating….zzzzzz.
absolut said:
January 8th, 2009 at 4:51 pm
As long as your analysis confirms atm consistently sucks, I couldn’t give a rat’s ass for the rest of the information. I do, however, really appreciate all the hard work and effort. What do you forsee for the USA’s IRR on TARP fund investments?
LonghornScott said:
January 8th, 2009 at 6:12 pm
Huck,
I’ve been toying with the idea of a similar analysis for a long time. The std dev of a good team is hugely important, imo. I think the final ranking you came up with there might just be the best ranking system I’ve seen.
wickedceltics said:
January 8th, 2009 at 6:30 pm
Seems like the idea of playoffs is the best way to go the more I hear about it. Down with the BCS!
Here’s a very relevant video about how the BCS robbed us Longhorns of our rightful shot at the title this year:
“BCS without the “C” – Texas should be #1
wickedceltics said:
January 8th, 2009 at 6:35 pm
maybe not as relevant as I originally thought…but I have to say that this had me laughing:
“I feel like I just gave birth… to an accountant!”
DrkBgrk said:
January 8th, 2009 at 7:19 pm
Now, who here likes a good story about a bridge?
pleaseplaykindle said:
January 9th, 2009 at 3:10 am
Teams with higher power ratings will naturally have higher standard deviation. Basically, I’m saying its easier to be consistently bad than consistently good. This seems trivial, but it has the effect that teams that have higher power ratings have more of an opportunity to deviate from them, whereas teams with low ratings do not.
Huckleberry said:
January 9th, 2009 at 8:56 am
Actually, the top 25 in the power ratings have an average consistency number of 12.9, while the bottom 25 have a number of 13.4 – this means that the top 25 were more consistent on average than the bottom 25.