In this article we will be describing the well known Rateform method. The Rateform method has its origins in The Rating Of Chessplayers by Professor Elo, and from the Punters Revenge by Tony Drapkin and Richard Forsyth. The basis of the Rateform method is that each of the two teams taking part in a match is given a point score that is based on their current form. Although this sounds very simplistic, and it is, its calculation is a little more involved.
Here are the basic rules…
1. Each team is given a point score representing their current form.
2. At the start of the season each team is given 1000 points.
3. When a match is played both teams contribute some of their points towards a kitty.
4. The home team supply more points into the kitty than the away team. This is done to reflect the home teams advantage of playing at home.
5. The winning team takes the kitty, unless the result is a draw in which case both sides share the points. In the case of a draw the away side gains points and the home side looses points.
Here is how a typical calculation is made…
home team points total = HTPOINTS
away team points total = ATPOINTS
home team contribution to kitty = HTKITTY = 7% of HTPOINTS
away team contribution to kitty = ATKITTY = 5% of ATPOINTS
the kitty therefore = KITTY = HTKITTY + ATKITTY
if the result is a HOME WIN then
home team receives KITTY points added to HTPOINTS
away team receives zero points added to ATPOINTS and looses its 5% contribution to the kitty
if result is an AWAY WIN then
home team receives zero points added to HTPOINTS and looses its 7% contribution to the kitty
away team receives KITTY points added to ATPOINTS
if the result is a DRAW then
home team receives KITTY / 2 points added to HTPOINTS
away team receives KITTY / 2 points added to ATPOINTS
Let’s look at a simple example of how you could apply this…
To calculate the possible outcome of a match based on rateform the away rateform is subtracted from the home rateform and the difference is compared against set values for home, away and draw possibilities.
For example we could make our set values as follows:
AWAY WIN -250 DRAW 150 HOME WIN
RATEFORM DIFFERENCE = HOME TEAM RATEFORM – AWAY TEAM RATEFORM
So, if the RATEFORM DIFFERENCE is less than -250 then the match is likely to be an away win, if the RATEFORM DIFFERENCE is greater than 150 then the match is likely to be a home win, and if the RATEFORM DIFFERENCE lies between then the outcome is most likely to be a draw.
Now it’s your turn…
Of course you may choose to use different values to those shown above and by experimenting you may come up with better values to use. You could also decide not to reset each teams points to 1000 at the start of the season but instead let them carry over into the next season. Another alternative would be to have a rolling calculation where you calculate the rateform for each team on say the last six months.