Author: Mike Byrne

Date: 11:57:59 01/04/04

Go up one level in this thread

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: >>> >>>>On January 04, 2004 at 11:46:00, Roger Brown wrote: >>>> >>>>>Hello all, >>>>> >>>>>I have read numerous posts about the validity - or lack thereof actually - of >>>>>short matches between and among chess engines. The arguments of those who say >>>>>that such matches are meaningless (Kurt Utzinger, Christopher Theron, Robert >>>>>Hyatt et al)typically indicate that well over 200 games are requires to make any >>>>>sort of statisticdal statement that engine X is better than engine Y. >>>>> >>>>>I concede this point. >>>> >>>>If you concede this point you don't understand. There is no magic number like >>>>200 or 2000. The score must be considered. Here is an example: >>>> >>>>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. >> >>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. > >Let's take a more obvious example. Let's say we play a 1000 game match and I win >by +20-0=980. I only score 51%, but if we then play a short match, your chances >of winning such a match is virtually zero, since the longer match has clearly >demonstrated you couldn't win a game if your life depended on it. But if you team needed a half point for you to win the Olympias, this is match up you wanted - a half point is a "shoo in" and you are the champs. Sometimes a draw is more important than a win and (in the example I used) is just as good as a win. Let's call the losing program "drawmaster" 98% of the games will end in draw - a coinflip that lands on the edge? > >Now compare this with the alternative possibility. We play a 1000 game match and >I win +510-490=0. Again 51%. Now we play a short match afterward, the match >outcome will be very nearly a virtual coin flip. Let's call this losing program "win_or_die" > >The first match is very convincing in demonstrating superiority. It is just as >effective as +20-0=0 is as per Remi. You may think so, but at the the end of the day, Dr Elo will have program "drawmaster" rated exactly the same as "win_or_die" --- and ratings are what we were talking about here. Which program you may want to use may be based on whether you need the win or a draw, if you need the draw , go with drawmaster, if you need the full point , your chances are better with "win_or_die" . > >The second match is very unconvincing in demonstrating my superiority. It showed >a game between us is a virtual coin flip. > >Draws matter a lot, but you need to understand just how. I'm very familiar with >what Remi has said on this and it was quite correct. The trouble is people >misunderstand what he has said. > >If you have understood the above, you will then understand that my remark to >Mike Young was right on the money. I understand the above, but you are mixing apples and oranges and in the context of the discussion taking place, your post was not on the money. It's really a different subject (imo) and you just added unneeded confusion to a discussion. > >> >>Peter

- Re: A question about statistics...
**Ricardo Gibert***16:22:43 01/04/04*- Re: A question about statistics...
**Sandro Necchi***01:13:21 01/06/04*- Re: A question about statistics...
**Sandro Necchi***23:07:08 01/06/04*- Re: A question about statistics...
**Rolf Tueschen***04:32:05 01/07/04*

- Re: A question about statistics...
- Re: A question about statistics... To SN
**Rolf Tueschen***06:18:57 01/06/04*

- Re: A question about statistics...

- Re: A question about statistics...

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