Glicko Ratings for NFL Teams

I’ve been reading a bit about different rating systems (such as the ELO Ratings used by FiveThirtyEight) and came across an intriguing rating system developed by BU professor Mark Glickman. They’re called the Glicko Ratings. One nice thing about Glicko ratings is that they allow you to calculate deviations, which is a rough measure of uncertainty in the rating.

So I’m going to try to work with Glicko ratings a bit this year, updated weekly in the newsletter and then the site. More details to come (including some technical info), but for now, here is a first cut at the weekly Glicko ratings for the NFC South in 2014. Click to enlarge.

initial glicko ratings

There are many things wrong with this initial analysis. For example, they assume that all the teams are equally good going into the season, which isn’t exactly true. FiveThirtyEight solves this problem by using prior-season ratings (accounting for some regression toward the mean) as an input for week one. I’ll do that eventually, which should make the ratings a little better. There are other optimizations to make, too, in time.

That said, this first cut looks pretty good to me.

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