A Note On Computer Ratings
by, 11-13-2012 at 01:02 PM (1107 Views)
Since College Sporting News produces the Gridiron Power Index (GPI) which is officially used by the NCAA D-I Football Championship Committee, I can speak with knowledge of computer rating systems that measure the Football Championship Subdivision (FCS).
The public GPI uses seven systems advised by Dr. Kenneth Massey as being representative as the best but one is different than the others. In conversations with the owners of these systems, all but one measured all the opponents of FCS teams and thereby produced valid results. The one that does not is the ratings of Jeff Sagarin.
The Sagarin ratings are created solely for use by the FBS in the Bowl Championship Series (BCS) since the beginning of the BCS. Dr. Massey has also created ratings used by the BCS since the beginning. The difference is the ratings by Massey are also valid for the FCS.
Sagarin treats all non-D-I schools the same. From D-II to NAIA, they all have the same rating in his system. So the 50+ games involving non-D-I squads are rated incorrectly. I asked him if he would consider rating all the teams and he refused. The Massey ratings comprehensively rates all teams correctly.
In the request from the NCAA for the GPI they stipulated that we not include the Sagarin ratings.
So please consider these facts when considering the Sagarin ratings alone. In fact, Massey advised that the GPI should use multiple ratings in such a way to achieve the best results. The GPI reflects this as being a top indicator of at-large playoff selection since the GPI began.