Tuesday, October 2, 2012

College Football Week 5 BCS Algorithm Ratings and Rankings - A first look at a BCS compatible algorithm

I post my regular ratings starting with week 1 of the season, but also calculate a set of ratings using a BCS compatible algorithm.  The latter does not use margin of victory, which makes it a far less accurate predictor of games, and also makes the ratings frankly pretty silly looking the first few weeks of the year, so I haven't posted them until this week.

The top-25 is below, and you will see that Florida is #1 here as they are in the regular ratings.  LSU makes a big move to #2 and they are followed by K-State, Georgia, and Oregon State.

Where is Alabama?  They are down at #9.  Understanding why this is can be educational as to why the BCS handicaps the computers.

Alabama has played a 2-loss Michigan, a 2-loss Mississippi, 4-loss Arkansas and Florida Atlantic, and a 1-loss Western Kentucky.  Because the computer can't take into account the margin of victory, while undefeated, the schedule isn't that strong and no single team is very strong.

LSU on the other hand just made a big leap and is rated higher because they beat a 1-loss Washington who also beat a 1-loss Stanford who beat a 1-loss Southern Cal.  So even though their average schedule is weaker, they have a very good quality win.

And Florida just has a much stronger average schedule.

What about Oregon?  They are way down at #13 and haven't played a team with fewer than 2 losses.

Most of the computers the BCS uses don't publish ratings early in the year because of the challenges with rating a team properly when you don't use the score, but also because most of the algorithms haven't been tuned to do so.  The result is some pretty fishy looking rankings.

Kenneth Massey does publish his and presently has a top-3 of Oregon State, Notre Dame, and Texas Tech.  Alabama is #8, Oregon #16, and LSU #13.  Not completely far fetched, but also likely not that accurate.  To be fair, Ken does have an algorithm that does use the score and it has Alabama #1, Oregon #4, and LSU #6.

Billingsley also publishes, but he also assumed starting rankings from the end of last year which would seem to be a violation of the rules for a BCS computer.  This is how he manages to have reasonable results.  Of course, he still has Michigan in his top-20 (#19) and Arkansas in the top-50!

Colley has rankings published and similar to Massey has Oregon State and Notre Dame at the top.  Jeff Sagarin also publishes and has the most reasonable results.

1Florida83.0364-067.454+0, -3.685
2LSU81.6925-059.142+8, +2.887
3Kansas St81.4914-058.859-1, -2.570
4Georgia80.9495-061.141+1, -0.981
5Oregon St79.6233-071.840+14, +3.534
6Notre Dame79.5214-066.180+0, -2.399
7Texas Tech79.0764-062.836+9, +2.333
8Florida St78.6345-055.935-5, -4.855
9Alabama78.2495-062.625+4, +0.341
10South Carolina77.8745-065.503-1, -1.941
11Texas77.3854-064.832-4, -4.534
12Washington76.4863-164.891+33, +6.256
13Oregon75.6435-056.819-9, -7.198
14West Virginia75.5464-060.318+15, +2.378
15Ohio State75.4715-061.891+26, +3.904
16Stanford75.3513-169.083-8, -5.113
17Mississippi St74.7734-055.802+8, +0.910
18Texas A&M74.7543-163.281-7, -3.588
19Clemson74.5634-165.003-5, -2.618
20Iowa St73.6633-165.960+2, -1.191
21Rutgers73.5484-060.380+18, +1.832
22Missouri73.0803-269.552+1, -1.147
23Oklahoma72.9522-161.389-3, -2.914
24Purdue72.6413-165.204+3, -0.746
25Tennessee72.4603-263.555-13, -5.599