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ed

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hi i am trying to calculate my level in case of victory/defealt
i have followed the help of this web site
i calculate
d=(hislevel-mylevel)/400
then
h=1/(10^d+1)
h is a number between 0 and 1
h is 0 if hislevel >> mylevel
h is 1 if hislevel << mylevel
then i make, what seems to me not very symmetric:
delta = 32*(1-h) where 1 means that i have won
delta = 32*(0-h) where 0 means draw
delta = 32*(-1-h) where -1 means that he has won
delta is the variation of my level
but it seems that it does not work
for example
i was 1219 and he was 1420
i have won
i am 1243 and he is now 1407
my predictions with these formulas had said that
i would be 1251 and he 1388

i guess, that something could be wrong with something i did not understand about a +400 or -400 in case i win or he wins.

thank you for your help !

divegeester
watching in dismay

STARMERGEDDON

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Try here for info on rating calculations:

FAQ

Kewpie
Felis Australis

Australia

Joined
20 Jan 09
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Here's a ready reckoner: Thread 80000

moon1969

Houston, Texas

Joined
28 Sep 10
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Clock
15 Jun 11
1 edit
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Originally posted by elo douwen
hi i am trying to calculate my level in case of victory/defealt
i have followed the help of this web site
i calculate
d=(hislevel-mylevel)/400
then
h=1/(10^d+1)
h is a number between 0 and 1
h is 0 if hislevel >> mylevel
h is 1 if hislevel << mylevel
then i make, what seems to me not very symmetric:
delta = 32*(1-h) where 1 means that i have wo ...[text shortened]... 1 means that he has won
delta is the variation of my level
but it seems that it does not work
Your scores are not correct. You have 1, 0, and -1. It instead should be 1 (win), 0.5 (draw), and 0 (loss).

delta = 32*(1-h) where 1 means that i have won
delta = 32*(0.5-h) where 0.5 means draw
delta = 32*(0-h) where 0 means that he has won



Below is the equation from the site I put into Excel and I thought it worked fine.

New Rating = Old Rating + 32 * (X - 1 / (10^((A-B)/400)+1))

where X is 1 for a win, 0.5 for a draw and 0 for a loss.
A = OpponentRating
B = YourRating

moon1969

Houston, Texas

Joined
28 Sep 10
Moves
14347
Clock
16 Jun 11
1 edit
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Originally posted by elo douwen
d=(hislevel-mylevel)/400
then
h=1/(10^d+1)
h is a number between 0 and 1
h is 0 if hislevel >> mylevel
h is 1 if hislevel << mylevel
I wasn't sure why you were looking at when h goes to 0 and when h goes to 1, except maybe you were generally evaluating the behavior of the equation.

What the h extremes of 0 and 1 mean to me is that it gives boundaries of max loss in points of 32 for a loss, a max gain in points of 32 for win, a max gain in points of 16 for a draw, and a max loss in points of 16 for a draw.

If your rating is much higher than your opponent (thus h = 1), your rating
-stays the same (no gain) if you win,
-you lose 16 points if you draw, and
-you lose 32 points if you lose.

If you your rating is much lower than your opponent (thus h = 0), then
-you gain 32 points if you win,
-gain 16 points if you draw, and
-your rating stays the same (no loss in points) if you lose.

There is the nuance that the constant 32 will change for higher ratings.

Another point to consider is where you and your opponent's ratings are equal. Thus, h = 0.5. In this case, you gain 16 points if you win, no change if you draw, and reduce 16 points if you lose.

Overall, it is symmetrical in a sense. You did have those correct scores for win/draw/loss which I guess made it seem not symmetric.

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