Re: [eia] Prussian rolls at Leipzig

[Joel Uckelman <uckelman@xxxxxxxxx>]

Thus spake Michael Gorman:
>
> Sigh.  I'm going back to the pbm dice server.  It likes me.  The nomic one 
> always rolls bad.

In the interest of fairness, I decided to do some analysis on the dice
server's random number generator to make sure that it's working properly.

I took a sample of 1m rolls of a d2, converted that to bytes, and ran it
through Ent. Here's what I got:


[uckelman@scylla tmp]$ ./ent <c
Entropy = 7.996935 bits per byte.

Optimum compression would reduce the size
of this 62501 byte file by 0 percent.

Chi square distribution for 62501 samples is 267.50, and randomly
would exceed this value 50.00 percent of the times.

Arithmetic mean value of data bytes is 127.1886 (127.5 = random).
Monte Carlo value for Pi is 3.166282642 (error 0.79 percent).
Serial correlation coefficient is -0.008664 (totally uncorrelated = 0.0).


Conclusion: These are very close to the values you'd get from a large, true
random sample, say from a radioactive source. Recall that the reason I set up
my own dice roller was due to the excessive latency of the one at pbm.com; I
doubt that that's changed, so I'd recommend sticking with mine. It's up to
you, though.

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