Author: Bruce Moreland
Date: 16:05:30 06/07/00
Go up one level in this thread
On June 06, 2000 at 15:53:44, Wayne Lowrance wrote: >All of the probobability details boil down to Junior having about as much >chance of beating Crafty 10-0 as I do winning the lotto, ok, exagerated but the >result from my perspective is wrong, something is wrong, I agree with Dr Bob's >assessmenmt. I am a educated EE (retired)and If one of my staff engineers came >to me with a similiar test result of his project, well, he would know better not >to come to me with it, Period. You would be being too harsh. It's true that if you pick a random string of results, you shouldn't expect to see an improbable outcome. But if you can search through a series of sub-strings, looking for one that has an improbable outcome, you might very well find one, since you give yourself a lot of chances. I wrote a program that allowed me to test this. I did a series of matches. Each match was 30 tests. If a 60/40 probability came back on the 60 side, I scored a given test a success. If there was a string of 10 successes in a row in any match, I counted this match. It should have been very possible to predict the probabilities here exactly, but I figured a Monte Carlo simulation would be good enough. I ran 1,000,000 trials and 55,000 of them had a series of 10 successes in a row. Which is 5% of them, which sounds like not a lot, but it is really quite a lot given how rare a string of 10 successes in a row should be. If I use a 50/50 probability, I only get about 10,000 matches counted, and if I up it to 75/25, I get over 300,000, which is 30% of the matches. It seems like small differences in the probabilities used have a large effect upon the outcome. This doesn't simulate chess very well, since we have draws, but I think that I've shown the test shouldn't be summarily dismissed as unfair. It may have been an improbable outcome, but not necessarily so improbable that you'd suspect the test. The only thing I'm a little suspicious of is that the string was the last ten games, so I'd wonder if Crafty was a little sick or something. That could bear some investigating. bruce
This page took 0.01 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.