### Elo math

Posted:

**05 Sep 2008, 08:07**Hi all,

although I'm not really mathematicly challenged, I'm can't really figure this one out. I'll first explain, then try to make sense.

At our chessclub, the children play in 4 (rising strength) groups (pawn,knight,rook,king) of about 16. I have wriiten new software to make the pairings, keep te scores etc, since the old program was written in DOS and hardly anybody could work with it.

Normally the children would only play outside their group, if it solves an odd amount in 2 groups.

I also calculate the rating for the children. What I do after every round, is calculate the winning chances for both players, look at the actual score, and add/substract the difference times 32. (k=32, as adviced by FIDE)

What happened with the old software was that the number 3 of the pawn group (lowest) could end up with the same rating as the number 3 of the knight group, while (mostly) you want them to end up with an elo of about the number 3 from the end of the knight group.

Questions:

Is this normal, or was the old program wrong ?

Is this solvable ?

IMO the problem is that the groups behave lindependent, and have too little relation to eachother.

One solution could be to lower the k-factor when someone reaches the toprating of his group. Anybody experience with that ? Is that mathematicly defendable ?

Cheers,

Tony

although I'm not really mathematicly challenged, I'm can't really figure this one out. I'll first explain, then try to make sense.

At our chessclub, the children play in 4 (rising strength) groups (pawn,knight,rook,king) of about 16. I have wriiten new software to make the pairings, keep te scores etc, since the old program was written in DOS and hardly anybody could work with it.

Normally the children would only play outside their group, if it solves an odd amount in 2 groups.

I also calculate the rating for the children. What I do after every round, is calculate the winning chances for both players, look at the actual score, and add/substract the difference times 32. (k=32, as adviced by FIDE)

What happened with the old software was that the number 3 of the pawn group (lowest) could end up with the same rating as the number 3 of the knight group, while (mostly) you want them to end up with an elo of about the number 3 from the end of the knight group.

Questions:

Is this normal, or was the old program wrong ?

Is this solvable ?

IMO the problem is that the groups behave lindependent, and have too little relation to eachother.

One solution could be to lower the k-factor when someone reaches the toprating of his group. Anybody experience with that ? Is that mathematicly defendable ?

Cheers,

Tony