Multiply all of those factors together, and you have the total number of Elo points that should shift from the loser to the winner in a given game. To combat this, we scale down the margin-of-victory multiplier for teams that were bigger favorites going into the game.

Since Elo gives more credit for larger wins, this means that top-rated teams could see their ratings swell disproportionately over time without an adjustment. In football terms, that means the Elo ratings of good teams run the risk of being inflated because favorites not only win more often, but they also tend to put up larger margins in their wins than underdogs do in theirs. Technically speaking, autocorrelation is the tendency of a time series to be correlated with its past and future values. eginThis factor also carries an additional adjustment for autocorrelation, which is the bane of all Elo systems that try to adjust for scoring margin.

This process is repeated for every game, from kickoff in September until the Super Bowl.įor any game between two teams (A and B) with certain pregame Elo ratings, the odds of Team A winning are: After the game, each team’s rating changes based on the result, in relation to how unexpected the outcome was and the winning margin. Those ratings are then used to generate win probabilities for games, based on the difference in quality between the two teams involved, plus adjustments for changes at starting quarterback, the location of the matchup (including travel distance) and any extra rest days either team had coming into the contest. In essence, Elo assigns every team a power rating (the NFL average is around 1500). The nuts and bolts of that system are described below. Way back in 2014, we developed our NFL Elo ratings to forecast the outcome of every game. The sport we cut our teeth on, though, was professional football. FiveThirtyEight has an admitted fondness for the Elo rating - a simple system that judges teams or players based on head-to-head results - and we’ve used it to rate competitors in basketball, baseball, tennis and various other sports over the years.

Nfl games week 1 point spread