Wednesday, September 22, 2010

Week 3 Rankings

Hey college football fans! I’ve had two weeks of hell at work (hence no week 2 post) but at least I have college football to look forward to on Saturday.

It’s only been three weeks but we’re starting to see some separation at the top of the rankings. Oregon and Alabama (ranked #1 and #2, respectively) have turned in the most impressive early season performances. Both have cruised to three easy victories. Oregon has put up more points but Alabama has played a slightly tougher schedule. There is a four point gap between Alabama and the next four teams in the rankings – Boise State, TCU, Ohio State and Nebraska. All four have been impressive early but Boise State and TCU will be fighting the perception that their success is primarily due to playing in weak conferences for the rest of the season. The big surprise in the top 10 is #7 Stanford. Jim Harbaugh has the LSJU Fighting Trees playing good football and has this Notre Dame fan nervous for Saturday. We’ll learn more about Stanford on October 2nd when they play Oregon. Florida, LSU and Oklahoma round out the top 10; all three are undefeated but have been inconsistent early.


P(WARG)* Rank Rank Team P(WARG)*
1 3 Boise State 0.683
2 1 Oregon 0.621
3 4 TCU 0.570
4 5 Ohio State 0.260
5 6 Nebraska 0.260
6 2 Alabama 0.190
7 20 Utah 0.033
8 10 Oklahoma 0.030
9 35 Nevada 0.024
10 9 LSU 0.020
11 7 Stanford 0.018
12 14 Texas 0.016
13 44 Fresno State 0.011
14 8 Florida 0.009
15 32 Wisconsin 0.007
* P(WARG) = Probability of Winning All Remaining Games.


The separation between the top 6 and everyone else is more obvious when we consider the probability of finishing undefeated. All three have at least a 19% chance of finishing undefeated, while the next highest (Utah) only has a 3.3% chance of finishing undefeated. Boise State has their second big test of the season Saturday against Oregon State. They shouldn’t be tested by anyone in the WAC and will be a virtual lock to go undefeated should they win on Saturday. Oregon is the most likely team to go undefeated among the BCS conference schools. Although, I think a 62.1% chance of going undefeated represents an overestimate. Ohio State, Nebraska and Alabama will have a tougher time going undefeated with Nebraska and Alabama facing the added challenge of a potential conference championship game to end the season.

Enjoy the weekend!

The week 3 rankings can be found at my personal website:

Friday, September 10, 2010

Week 1 Rankings!

Hey college football fans! I hope you enjoyed the first weekend of the season. I know I did!

The dream is still alive in Boise. The Broncos posted the most impressive win of the weekend by defeating Virginia Tech 33-30 in a neutral site game that was essentially a home game for the Hokies. LSU and TCU were the only other teams to defeat members of the pre-season top 25 with victories over North Carolina and Oregon State, respectively, although, North Carolina was without several regulars due to suspensions for various off-the-field shenanigans. Alabama, Ohio State, Nebraska and Oregon were also impressive with big victories against overmatched opponents, while Florida, Texas, Oklahoma and USC had disappointing opening weekends with lackluster performances in victories over very mediocre competition.

The rankings changed quite a bit after week 1 but that is to be expected during the first couple of weeks. The rankings should start to stabilize after the first month of the season. Oregon jumped up to number 1 after their 72-0 victory over New Mexico. TCU, LSU, Florida State and Georgia moved into the top 10, while USC, Texas, Florida and Oklahoma dropped out. Oklahoma took the biggest tumble, dropping all the way to number 23 after their 31-24 victory over the mighty Utah State Aggies.

Here are the top 15 teams ranked by the probability that they go undefeated:


P(WARG)* Rank Rank Team P(WARG)*
1 3 Boise State 0.786
2 5 TCU 0.481
3 1 Oregon 0.324
4 2 Ohio State 0.254
5 26 Houston 0.127
6 7 Nebraska 0.088
7 4 Alabama 0.069
8 21 Utah 0.048
9 14 Wisconsin 0.047
10 15 Texas 0.034
11 9 Florida State 0.030
12 11 USC 0.025
13 8 LSU 0.023
14 10 Georgia 0.017
15 20 Iowa 0.010
* P(WARG) = Probability of Winning All Remaining Games.

Boise State was the big winner after week 1. They now have almost an 80% chance of finishing the season undefeated. Boise State's season essentially comes down to their matchup with Oregon State on September 25th. They'll still have to play good football for the rest of the season but they will be heavy favorites in all but the Oregon State game. TCU also looks like a good bet to go undefeated but it’s unlikely that they’ll play for the national title unless Boise State loses. Oregon and Ohio State are the best bets among the BCS conference schools but I think the probabilities presented above are overestimates due to instability in the model this early in the season.

Enjoy the weekend!

The week 1 rankings can be found at my personal website:

www.biostat.umn.edu/~josephk/wk1_ranking_report.pdf

Thursday, September 2, 2010

Pre-Season Rankings

Hello college football fans! The season kicksoff tonight with an interesting match-up between Pitt and Utah to go along with the usual slate of early-season body bag games. My pre-season rankings can be found on my personal web page:

www.biostat.umn.edu/~josephk/ps_ranking_report.pdf

First, a quick summary of the rankings. I rank college football teams using a Bayesian hierarchical model that incorporates margin of victory. The pre-season rankings serve as the prior distribution for the model and are a combination of “expert” opinions about the relative strength of teams before the season starts (specifically, the pre-season rankings from Yahoo, Athlon and Lindy’s). I update the model every Sunday once new results are available. Using the updated model, I simulate the remainder of the season 10,000 times, which allows me to estimate a team’s expected final record, probability of winning all of their remaining games, etc. I will provide a more detailed description of the model and simulation on my methodology page for those that are interested.

The pre-season rankings are simply a combination of published pre-season rankings and reflect the general consensus going into the season. Alabama is the unanimous number 1, followed by Ohio State, Boise State, Florida, Texas, Nebraska, Oklahoma, USC, Virginia Tech and Oregon. I have two quick comments on the top ten. First, the Oregon Ducks made weekly appearances in the police blotter during the offseason (although, none were as strange as the recent arrest of an offensive lineman at rival Oregon State) and, depending on when the rankings I used for the prior were published, the pre-season rankings may not reflect that quarterback Jeremiah Masoli was dismissed from the team. Oregon is still a contender for the Pac 10 title but losing Masoli will hurt. Second, USC had a tumultuous offseason culminating in being placed on probation for the Reggie Bush fiasco. The Trojans are not bowl eligible and can’t receive votes in the Coaches Poll but they still look like the strongest team on the West Coast.

Here are the top 15 teams ranked by the probability that they go undefeated:

P(WARG)* Rank Rank Team P(WARG)*
1 3 Boise State 0.412
2 11 TCU 0.322
3 33 Navy 0.144
4 2 Ohio State 0.130
5 8 USC 0.095
6 31 Houston 0.094
7 6 Nebraska 0.090
8 12 Iowa 0.087
9 10 Oregon 0.085
10 13 Wisconsin 0.081
11 5 Texas 0.072
12 1 Alabama 0.065
13 4 Florida 0.034
14 7 Oklahoma 0.030
15 9 Virginia Tech 0.030

P(WARG) = probability of winning all remaining games

One of the most interesting storylines of the season is Boise State’s quest for a national title. They are a legitimately elite team but, more importantly, their schedule is much weaker than the other national title contenders. They will have an excellent chance of running the table if they defeat Virginia Tech on Monday night. TCU is in a similar position to Boise State but probably starts the season ranked too low to have a legitimate shot at the national title. The title contenders from BCS conferences have a much tougher road to the national title. Even as the unanimous number 1, Alabama only has a 6.5% chance of going undefeated. Ohio State has the best chance of the BCS crowd but still only has a 13% chance of going undefeated. Finally, I’d be remiss if I didn’t discuss the #3 team on this list: Navy. The Midshipmen have had a great run over the last few years and are expected to be a solid, top-30 caliber football team. Their schedule is incredibly weak and they have a very real shot at going undefeated. Can they make the BCS? We’ll see? It would be a great story for sure.

Have a good one. I can’t wait until kickoff!

Wednesday, September 1, 2010

Welcome to my blog!

Hello and welcome to my blog! In this blog you will find discussion of my statistical model for ranking college football teams. I developed the rankings during the 2007 college football season and have been sharing them via email with a group of friends and family ever since. Last season, a friend suggested I start a blog, saying, “You should start a blog. Seriously, people will read it.” I’m not sure if I believe her but I thought I’d give it a shot. Statistical models for ranking college football teams have been developed for decades and I can’t, honestly, say that my rankings are any better than what is currently available but I think I provide some summaries that are unique and that will be of interest to college football fans. I’ve had a blast sharing my rankings with friends and family over the last few years. I hope you will enjoy them too!