College Football Playoff

[IrishAZ]

If you're not familiar with an ELO rating - it's simply a system where one's rating goes up or down depending on the strength of the team you face. ELO goes up more if you beat a higher rated team, and down more if you lose to a lower rated team (and up less beating a lower rated team and down less losing to a higher rated team).

 

This is the system that's incorporated into Sagarin's rating system in USA Today if you're familiar with that.

 

OK but isnt an ELO system still flawed bcuz computing these rankings based on SOS is in itself arbitrary no? how are the original rankings contrived? by polls which are themselves subjective so now youre in a perpetual circle J.

Well, not precisely.

 

ELO is calculated using the formula:

 

Rn = Ro + C * Se.

 

New Ranking (Rn) = Old ranking (Ro) + A constant © times the expected score (Se) based on the ranking difference..

 

The expected score is based on a table value. Two teams that are equal in ELO have an expected score of .5 - teams that are separated by 100 ELO have an exptected score of .65.

 

If you assume that every team starts out with an ELO of 1000 and you use a constant of, say, 50.

 

The winners of the first game of the year would have an ELO of 1025 (1000 + 50 *.5)

 

The losers of the game would have an ELO of 975.

 

If a 1-0 team beats another 1-0 team, their new ELO becomes 1050 (the loser's becomes 1000).

 

So, as teams win, their ELO goes up, as they lose it goes down. Losing to a more powerful team nets a smaller loss than losing to a weaker opponent, and so on.

 

I've not studied statistics for a while, but I think a field of 117 teams would stratify nicely after about 8 iterations or so (leaving about 15 teams on average per score group - 8-0, 7-1, 6-2, etc.).

 

That make any sense?

 

IRISH!