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Re: [Bug-gnubg] Dice Rolls

From: JD
Subject: Re: [Bug-gnubg] Dice Rolls
Date: Fri, 16 Aug 2013 22:11:29 -0600
User-agent: Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/20130625 Thunderbird/17.0.7

On 08/16/2013 09:59 PM, Russ Allbery wrote:
JD <address@hidden> writes:

While you can do a statistical study of the randomness of dice rolls, it
does not take into account that the engine can see current board, and
determine that it (the gnubg pseudo-player, which is also me - since I
selected human against human, and player 0's default name is gnubg). I
find it very strange that in 4 out of 5 games, where I was playing both
as player 0 and player 1, with player 0 being gnubg, the rolls for gnubg
were incredibly winner rolls - totally amazing to me.
So, I was not playing against the bot, as you say. I was playing human
against human, and I did not enable the "Dice Manupulation" option at
But I can tell you in all honesty that I was doing my best for each roll
of the dice for both players (0, and 1).
The problem, in a nutshell, is that your sample size is much too small.

Humans (all humans) have a very bad intuition for randomness.  We expect
it to be more uniform than it actually is, when in reality it's quite
clumpy and prone to long patterns of behavior that we think of as not
random.  This is why, for example, many slot machine players will
absolutely swear that there is such a thing as hot and cold machines, or
that a machine is "ready" to pay out, when under the hood the slot
machines have government-certified mathematical random number generators
that don't care in the slightest about whether they've paid off recently
or not.

We're very, very good at finding patterns.  It's what our brains are
adapted to do.  We therefore find patterns even when they don't exist,
possibly since (evolutionarily) it's a survival characteristic to err on
the side of seeing patterns (e.g., predators) where they don't exist
instead of erring on the side of missing patterns that do exist.

In any event, five games is far, far too few to tell you anything of
substance (as you alluded to in your earlier message).  You'd need to do a
more systematic and recorded study across more like 100 games, with some
sort of objective criteria, to be sure that the pattern is statistically

Yes, correct.
All I am saying is that TO ME, it is sufficiently significant, because
I will certainly NOT be playing millions or billions of games and note
the rolls for each given board state.
Up to now (as of typing this message), I have played about 10 games,
and out pf 10 games, of 7 points each, I won only one game, even then,
marginally. I lost 9 games, and each one with a huge disadvantage in
the number of my pieces remaining on the board.
Certainly, I did not set out to lose to myself.
I would have hoped that the engine would not suddenly roll dice that
would provide doubles to player 0 in the most amazingly opportune time,
to to roll dice that would hit my piece exactly when it became uncovered.
NO such dice would roll for player 1. NONE!!!!
In 10 games, each game with 5 or 7 points.

I am sorry, this may not be statistically significant to mathematicians.
It is extremely significant to me, as I do not have the time to put in
100,000,000 games.

Best regards,


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