From: onar@hsr.no (Onar Aam)
Subject: The ICS rating system (was Re: Why I Hate the ICS rating system.)
Organization: Rogaland University Centre
Date: Thu, 5 Nov 1992 06:47:11 GMT


>|> This is not true. If I understand the system correctly then 1000 points are a
>dded
>|> to the pool each time a new player enters. And this makes the 1000 rating an
>|> attractor for the whole system. The average is converging towards 1000. By
>|> setting the provisional rating to the average of the international rating the
>|> system as a whole will slowly recover. I agree that a provisional rating of 1
>500
>|> will fix the problems of ICS.
>
>It seems to me that with the +/- 400 thing, 1000 is not an attractor, and 
>1000 is not what people start with, thus ratings arent' deflated taht much.
>
>for example during the first 20 games if i play someone 400 points lower than
>me and win they lose one and i don't gain any.  This seems to be the only case
>where points aren't put into the system.
>
>If i play someone my level, i gain 400 points( to be averaged) while they only
>lose 16.  if i play someone 400 points higher than me they lose 32 and 800 points
>get averaged into my score.  Unless i play really bad i should start out with a
>score between 1100-1200 (granted this is well below the 1500 people have stated
>are good starting places.
>Of course my math isn't strong, and i might not be fully comprehending waht's 
>going on with the rating sytem , but does this seem reasonable?

It sounds reasonable enough but you missed a little point. In your very first
game the server treats you as if you are rated to 1000. This does not affect your
own rating since that follows the "+/- 400 thing" BUT your opponent is affected
by it. Imagine that you are a 2000 player and in your first game you play someone
rated at 1500. It is most likely that your opponent will lose to you since you in
real life are a lot better than him. AND , the crucial point, he loses 31 points
because the server assumes that you are a 1000 player. These 31 points are lost
forever. And this means that the total number of points in the pool on
average will decrease until 1000 equals the average rating of all the players.
    
Lets for a sec. imagine that the provisional rating is 2000. What would happen
then? 2000 is above average and therefore the average would rise until it reached
2000. Ex. A player rated 1000 plays his first game against a 1500 player. the
1500 player is most likely to win BUT the server thinks that the new player is
rated 2000 and therefore the 1500 player gets 31 points out of nowhere. (He would
normally only get one point) And the average would slowly rise till it reached
2000.


  

>In article <1992Nov3.195552.13132@oucsace.cs.ohiou.edu>  
>jacobson@oucsace.cs.ohiou.edu (Eliot T. Jacobson ) writes:
>>   RAISE THE INITIAL PROVISIONAL RATING FROM 1000 TO SOMETHING MORE REALISTIC.
>
>Unless the current administrators have changed something, there is _no_ initial  
>provisional rating. You only acquire a rating after you play your first rated  
>person. If you win you are their rating + 400, if you loose you are their  
>rating - 400, or if you draw you get their rating.

This is an indirect rating. The server "pretends" you have an initial rating of 
1000. As I said this does not affect your own rating but rather your
first opponent.

 


>I do agree that ICS ratings are way below USCF or FIDE ratings. I also agree  
>that the average rating seems to be dropping. I think it is because more weak  
>players (like me) have been joining.

In fact, if an abnormally large number of below-average people entered the net
they would in fact skew the net back up again! The average would still be
sinking, but each player's rating would get closer to their FIDE rating. 



Someone mentioned that there was a skew problem even when the provisional rating
was 1500. The reason for this is unclear. I cannot imagine that the rating system
is intrinsically skewish since it is directly based on the ELO rating system.
Therefore there must be other reasons. But putting the provisional rating back up
to 1500 will definitely help. That I can guarantee.


Onar.