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Subject: Re: Maybe a stupid experiment...

Author: Ricardo Gibert

Date: 14:34:30 01/04/01

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On January 04, 2001 at 02:38:42, Uri Blass wrote:

>On January 04, 2001 at 00:00:39, Robert Hyatt wrote:
>
>>On January 03, 2001 at 17:50:38, José Carlos wrote:
>>
>>>On January 03, 2001 at 16:26:19, Robert Hyatt wrote:
>>>
>>>>On January 03, 2001 at 09:52:06, José Carlos wrote:
>>>>
>>>>>  Lately, people have been talking here about significant results. I'm not
>>>>>really sure if probabilistic calculus is appropiate here, because chess games
>>>>>are not stocastic events.
>>>>>  So, I suggest an experiment to mesure the probabilistic noise:
>>>>>
>>>>>  -chose a random program and make it play itself.
>>>>>  -write down the result after 10 games, 50 games, 100 games...
>>>>>
>>>>>  It should tend to be an even result, and it would be possible to know how many
>>>>>games are needed to get a result with a certain degree of confidence.
>>>>>  If we try this for several programs, and the results are similar, we can draw
>>>>>a conclusion, in comparison with pure probabilistic calculus.
>>>>>
>>>>>  Does this idea make sense, or am I still sleeping? :)
>>>>>
>>>>>  José C.
>>>>
>>>>It is statistically invalid.  IE if you flip a coin 500 times do you _really_
>>>>expect to get 250 heads and 250 tails?  Probability distribution says you
>>>>won't get that very often at all.  In fact, if you flip long enough, you will
>>>>either get 500 straight heads or tails, or else prove the coin is _not_ actually
>>>>perfectly random with  50-50 probability of getting a head or tail.
>>>
>>>  But don't you think the more times you flip the coin, the closer the number of
>>>head and tails (in %) will be? Maybe the coin is not the better comparison, as
>>>it is a random event, and a chess game is not, but I still think it should work.
>>>But I expect a different rate of "closeness" (is this word correct?) for the
>>>same number of tries with the coin (random event) and the games (partially
>>>random -book, pondering, ... and partially not -eval function, search algos...),
>>>and that difference is what I want to measure.
>>>
>>>  José C.
>>
>>
>>No I don't.  Suppose that 500-0 run comes _first_.  How long will you have to
>>flip to get back to even?  You may _never_ get back to even.  Remember this is
>>a bell-curve shaped probability distribution.  Not a single spike on the curve
>>at the mid-point of the distribution.  You probably need to play 40 forty-game
>>matches to get the beginning of an idea of who is better.
>
>You replied to the sentence:
>"But don't you think the more times you flip the coin, the closer the number of
>head and tails (in %) will be?"

Bernoulli's Theorem says yes to this question (for a fair coin).

>
>I think that you missed the in %
>
>Uri



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