Computer Chess Club Archives


Search

Terms

Messages

Subject: Re: Standard deviations -- how many games?

Author: Bob Durrett

Date: 18:08:27 01/23/04

Go up one level in this thread


On January 23, 2004 at 15:24:31, Dann Corbit wrote:

>30 experiments is a fairly standard rule as to when you should start to trust
>the results for experimental data.
>
>From:
>http://www.twoplustwo.com/mmessay8.html
>"A good rule of thumb is to have at least 30 observations (playing sessions) for
>the estimate to be reasonably accurate. However, the more the better, unless for
>some reason you think the game for which you are trying to estimate your
>standard deviation has changed significantly over some particular period of
>time."
>
>From:
>http://www.odu.edu/sci/xu/chapter3.pdf
>"C. The Reliability of s as a Measure of Precision - the more measurements that
>are made, the more reliable the value obtained for s. Usually 20 - 30
>measurements are necessary."
>
>From
>http://www.stat.psu.edu/~resources/ClassNotes/ljs_21/ljs_21.PPT#11
>Concerning the central limit theorem, we have this:
>Even if data are not normally distributed, as long as you take “large enough”
>samples, the sample averages will at least be approximately normally
>distributed.
>Mean of sample averages is still mu
>Standard error of sample averages is still sigma/sqrt(n).
>In general, “large enough” means more than 30 measurements.
>
>
>Of course, the more the merrier, when it comes to measurements.

I don't wish to muddy the waters too much but the fact is that chess-playing
programs or machines do not enter tournaments with zero information known about
them.  Just as in human tournaments, prior knowledge known prior to any games
being played in the tournament can be very significant.

Consider a trivial example:  Suppose a top GM is to play a chess match against a
true chess beginner.  It is known apriori that the top GM is a whiz at chess and
the beginner is a washout.

Will it take thirty games to determine who is better?  No, it will take ZERO
games.

The number of games required depends on the prior knowledge about the
contestants.

I hope this is not too distressful for anybody.  : )

Bob D.



This page took 0 seconds to execute

Last modified: Thu, 15 Apr 21 08:11:13 -0700

Current Computer Chess Club Forums at Talkchess. This site by Sean Mintz.