You might hear or see reference to the World Football Elo Ratings during the 2014 World Cup. The teams opening the World Cup, Brazil and Croatia, have Elo Ratings of 2113 and 1787 respectively.
Elo Ratings are based on the work of Arpad Elo. The Ratings were developed for chess but they have been adapted for other games, including football.
Bob Runyan developed the first Elo Ratings for football in 1997. In these Ratings, there is:
- a weighting for the kind of match played;
- an adjustment for home team advantage;
- an adjustment for goal difference in the match result.
The formula used to calculate the Elo Rating is Rn = Ro + K × (W - We), in which:
- Rn is the new rating;
- Ro is the old (pre-match) rating;
- K is the weight constant for the tournament played (60 for World Cup finals);
- K is then adjusted for the goal difference in the game. It is increased by half if a game is won by two goals, by ¾ if a game is won by three goals, and by ¾ + (N-3)/8 if the game is won by four or more goals, where N is the goal difference;
- W is the result of the game (1 for a win, 0.5 for a draw, and 0 for a loss);
- We is the expected result from this formula. We = 1/(10(-dr/400)+ 1) in which dr equals the difference in ratings plus 100 points for a team playing at home.
Now that is clear, below are the Elo Ratings of all the teams at the World Cup as of June 2. Each team’s rating will be recalculated in the Elo system after each game played by that team.