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ggkfc
16-12-2007, 06:11 AM
Hey
I used to play in jcl, i was wondering if anyone still has the forumla? it was quite simple as i remember. but the only thing i can clearly get still is if rating difference > 400, its set as if it was 400. if anyone could pull out one of those chess mags and type the formula, it would be great. (i tried searching far and wide online to no avail =( )

thnx

Denis_Jessop
16-12-2007, 10:25 AM
Hey
I used to play in jcl, i was wondering if anyone still has the forumla? it was quite simple as i remember. but the only thing i can clearly get still is if rating difference > 400, its set as if it was 400. if anyone could pull out one of those chess mags and type the formula, it would be great. (i tried searching far and wide online to no avail =( )

thnx

If you go to http://www.nswjcl.org.au/Contacts/nswcontacts.htm you'll find an e-mail contact for the Ratings Officer, among others, who may be able to help.

DJ

Bill Gletsos
16-12-2007, 11:06 AM
Here is a copy of a post of mine from back in 2004 that describes the formula.


When I last looked at all this stuff back around 1999/2000 the rating formula seemed kludgy.
On top of that there appears no reliability in the conversion method from junior to adult ratings.
The system also has a rating floor round about 250.
Once your rating reached 250 your rating was not decreased by any formula but only by the number of successive losses you had. Apparently one of the lowest ratings was then 230 after 20 successive losses. A rating of 200 is supposed to be equivalent to a player who knows how to play but loses ALL games.


The rating formula they use is as follows (June-September 2002 (Number 93-94) NSWJCL magazine):

New Rating = old rating + C (C=Change)

Games are processed one at a time. For each game C is determined from:

C = (W + B*sqrt(D/400))*A*F*L

W = 0 if the game is drawn else W = 1 (The value W is applied to both players)
B = -1 if the higher rated player wins else B = +1 (Making C bigger for upset wins)
D is the difference in ratings for the two players (If D is greater than 400 it is set to 400)

A is a factor that varies with the status of the event. A varies from 10 for most games to 20 for the U18 at state or Australian Championships). Exception if your rating is decreasing then A=10.

F is a factor which varies with the result and relative ratings of players.
Winners and lower rated players who draw F = +1. (It is the postive sign of F that makes C positive, increasing the rating)
Losers: F = -0.7 (I have also seen this published as 0.8), Higher rated player who draws: F = -0.5. (It is the negative sign of F that makes C negative, decreasing the rating)

L is normally 1.


Now supposedly a rough conversion of NSWJCL ratings to adult ratings is as follows:
for ratings less than 600 then adult = 2*J
for rating greater than 600 adult = (J*1.25) + 450

Vlad
16-12-2007, 12:55 PM
You probably mean F=+1 rather than D=+1, which I believe just an obvious typo.

The second conversion formula works reasonably well except for the top juniors. In particular, if you apply the formula to Max Illingworth ratings - his junior rating is 1234, which converts to 1993; his actual ACF is 2224. The reason is that he is the top junior and does not have enough competition. So I would think the formula is only applicable for junior ratings roughly below 1000.

Bill Gletsos
16-12-2007, 01:53 PM
You probably mean F=+1 rather than D=+1, which I believe just an obvious typo.Correct and I have fixed it.

As I noted above the description of the formula was published in the June-September 2002 (Number 93-94) NSWJCL magazine.

The next time the rating system was described it was in the December 2005 Issue 105 of the NSWJCL magazine.

It was described there as follows:


New Rating = Old Rating + C

Games are processed one at a time, and for each game the change in rating (C) is determined from:


C = (W + B*sqrt(D/400))*A*R*L

W is determined from the result (Win/Loss/Draw) - if the game is drawn W = 0 otherwise W = 1. (W makes the changes for a draw smaller than the changes for a win/loss)

B boosts the change for upset wins. If the higher rated player wins then B = -1 otherwise B = +1

D is either the difference in ratings for the two players or 400, whichever is smaller

A is an achievement factor. Your successes in venets with greater status are worth more rating points to you. (This correlates to longer time limits on games). For large one-day events A = 10; for multi-day events it is more, up to 18 for the NSW Junior Championship. A is lower for teams events and for events restricted by age, rating, sex, region or time (but lightning events are not rated).

R varies with the resukt and the relative rating of the players. R = n+1 for winners and also for lower rated players who draw. (It is the positive sign of R which makes C positive, increasing the rating.) R is negative for losers and for higher rated players who draw, but to prevent a gradual "deflation" of overall ratings, R is -0.8 for losers and -0.5 for draws. These negative values are further reduced in magnitude in events like the finals in teams competitions.

L is a loading factor - normally 1, but sometimes used to modify C where players ratings are uncertain (e.g. where a team plays out of rating order.)The above was also repeated in the current issue 111 Spring 2007 of the NSWJCL magazine.

Vlad
21-12-2007, 11:47 AM
I think the only parameter in the above formula the description of which is vague is A. I guess the only way to know what A should be is to see a table of different values for different tournaments. Before the last ratings were published about 2 months ago I did calculations for Anton with A=10 for all tournaments he played in. I ended up getting +124, which was not far from the actual change +130.

On the other hand, in the above description it says that NSW junior championships are rated with A=18 and he was very successful in that competition. So I can see two possible explanations.
a) The under 12 NSW championship is rated with A=10 because it is restricted by age.
b) Some tournaments are rated with A<10.

mikesguns
23-10-2008, 04:00 PM
I play in Victoria. Do you know the rating formula?

Denis_Jessop
23-10-2008, 06:24 PM
I play in Victoria. Do you know the rating formula?

Victoria doesn't have junior ratings as far as I know. It doesn't have a Junior Chess League either.

DJ