# Computer Chess Club Archives

## Messages

### Subject: Re: A question about statistics...

Author: Ricardo Gibert

Date: 16:46:51 01/04/04

Go up one level in this thread

```On January 04, 2004 at 17:44:08, Dieter Buerssner wrote:

>On January 04, 2004 at 13:46:48, Ricardo Gibert wrote:
>
>>On January 04, 2004 at 12:47:25, Peter Berger wrote:
>>
>>>On January 04, 2004 at 12:40:00, Ricardo Gibert wrote:
>>>
>>>>On January 04, 2004 at 12:29:15, Mark Young wrote:
>>>>
>>>>>A score of 17 - 3 in a 20 game match has a certainty of over 99% that the winner
>>>>>of the match is stronger then the loser.
>>>>>
>>>>>A 100 game match ending 55 - 45 only has a 81% chance that the winner of the
>>>>>match is the stronger program.
>>>>>
>>>>>A 200 game match ending 106 - 94 only has a 78 % chance that the winner is
>>>>>stronger then the loser.
>>>>
>>>>
>>>>Nothing you have said is really correct because you have ignored the significant
>>>>effect of draws in a match.
>
>I think, I understand the issue you rise. However, 17-3 will be more significant
>than the other results independent of draw. So, still some truth there. I really
>wonder, how exactly Elostat calculates the +/- margins to the calculated rating.
>Does anybody know an URL, where one can read this?
>
>>>The percentage of draws doesn't matter at all when it is about the conclusion
>>>which program is strongest based on the above match results.
>>>
>>>This has been shown by Remi Coloum and explained in multiple posts
>>>here(unfortunately the search engine hasn't found a new home yet).
>>>
>>>6-0 with 0 draws and 6-0 with 1000 draws has the exact same prediction value
>>>when it is about the question which engine is stronger based on a match result.
>>
>>In this case, the number of decisive games (w+L=6) and margin of victory (w-L=6)
>>is the same in both cases so the conclusion they have equal value is correct.
>>
>>    -------------------------------
>>
>>In the examples given before, the number of decisive games depends on the number
>>of draws e.g. +17-3=0 and +14-0=6 are not of equal value since the number
>>decisive games are not equal.
>
>Hey, I think Peter and Ricardo wanted to say exactly the same thing. Still they
>succeeded to disagree.

??? Not exactly the same thing at all. He said, "The percentage of draws doesn't
matter at all when it is about the conclusion which program is strongest based
on the above match results." This implies that +55-45=0 is the same as +10-0=90
and I completely disagree with this.

>
>Regards,
>Dieter

```