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Subject: Re: how not to calculate performance

Author: James T. Walker

Date: 13:44:17 11/02/04

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On November 02, 2004 at 08:22:10, Sune Fischer wrote:

>On November 02, 2004 at 07:42:24, James T. Walker wrote:
>
>>Just plot a graph with 999 data points all with a value of zero.  Then plot
>>another graph of 1000 data points  all with a value of zero.  Then compare the
>>difference.
>>Jim
>
>Ratings can become negative, so zero is not the lowest rating possible you can
>get. Zero is actually an arbitrary number you just picked out of nowhere, you
>might as well have said -1000.
>
>The proof of this is easy, even without knowing the formula. Just consider the
>1400 guy and someone who is 400 ELO weaker, then consider one that is 400 ELO
>weaker than him and so on, you quickly get negative ratings.
>
>I don't know what the lowest rating is, even if you assume perfectly worst play
>your opponent might also be playing perfectly bad or close enough to that so you
>don't lose every time.
>You can thus never get an expected score of 0 and an equivalent rating of
>-infinity.
>
>-S.

What is your point?



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