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4. November 2009, 04:02:28
playBunny 
Subject: Re: Bias
pedestrian: I also did a very quick check using alanback's 21-pointer against furbster. It was the first and only match that I looked at.

Of the 12 games in the match, 5 started with the same roll for each player, although the order of the numbers was different in 3.

Game 1   61, 46
Game 2   23, 42
Game 3   12, 31
Game 4   14, 51
Game 5   13, 31
Game 6   45, 54
Game 7   15, 51
Game 8   41, 42
Game 9   41, 41
Game 10   13, 41
Game 11   65, 63
Game 12   31, 31

If it's coincidence then it certainly seems to be one that can be found without much effort.

ps. Abigail's right about the odds. It doesn't matter what the first roll is, the chances of the second matching it are dependant on the 36 possibilities for that second roll.

4. November 2009, 06:02:49
grenv 
Subject: Re: Bias
playBunny: oops, second roll can be doubles... gotta get some sleep.

4. November 2009, 10:39:10
Resher 
Subject: Re: Bias
playBunny: The reported order of the numbers within a roll isn't relevant is it?  Doesn't this just depend on whether a player swapped the numbers before using them?

I also checked my most recent two 21-pointers and found 6 out of 17 same initial rolls for both matches, so 35% compared with an expected percentage of less than 6% if they were independent.  I think this is statistically significant and wonder whether there is some circumstance where the first two dice rolls are determined at the same time (and so would always be the same), rather than when each player clicks on the game at different times?

4. November 2009, 17:42:53
grenv 
Subject: Re: Bias
Resher: If both numbers were generated at the same time, wouldn't you expect 100%..? To what do we attribute what is being seen.

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