The Rate Form system has its origins in Professor Elo's book "The Ragin of Chessplayers", which in turn was adapted for soccer by Tony Drapkin and Richard Forsyth, and described in their book "The Punter's Revenge" (Chapman and Hall).
As soccer matches (or football matches as you wish) are played over a season the points totals are updated for each team. Points totals carry forward from one season to the next, which makes it possible to do a comparison over the history!
The fundamental features are :
- each team has a points total which represents its current playing form
- the average number of points for all the teams remains almost constant at 1000
- for each match the home and away teams contribute points to a kitty
- the winning team takes the complete points kitty
- teams which draw share the kitty
The points which are contributed to the kitty are 7% for the home team and 5% for the away team for their totals. The team points totals are used as a guide to form. As before, the home team points minus the away team points gives a difference which is used to rate the forecast. The home team points contributes a higher percentage to include the home advantage in the calculation. The promoted teams start the new competition with the average points of the relegated teams, in such a way that the average of all the points is exactly 1000.
This Rate Form system is a perfect system over time, as the points are not calculated from scratch at the start of a new season. The following picture shows the performance of AC Milan over the past years. In the season '93-'94 AC Milan ended as the champion in the Serie A, as displayed in red. The next season they ended fourth place.
As you can see in the image, this form guide uses the previous years in the calculation, as the first position in 1999 is not "as good" as the one in 1996. The longer the strong sequence, the higher the rating.