RE: Simple algorithm question - how to reorder a sequence economically

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Subject	RE: Simple algorithm question - how to reorder a sequence economically
Date	Sat, 25 May 2013 00:33:01 +0300
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----------------------------------------
> Date: Fri, 24 May 2013 12:01:35 -0700
> Subject: Re: Simple algorithm question - how to reorder a sequence economically
> From: peter.h.m.brooks@gmail.com
> To: python-list@python.org
>
> On May 24, 5:00 pm, Carlos Nepomuceno <carlosnepomuc...@outlook.com>
> wrote:
>>
>>
>> I don't know what "spurious evidence of correlation" is. Can you give a mathematical definition?
>>
> If I run the simulation with the same sequence, then, because event E1
> always comes before event E2, somebody might believe that there is a
> causative connection between them in the world that's being simulated,
> when, in fact, they only correlate in this way because the sequence is
> not being shuffled. That's what it means.

Correlation does not imply causation. If "somebody" is an expert system and you want to avoid it's recognition and/or triggering of some kind, and you can't or don't want to change it's behavior, you may take the random way because it's cheaper.

> Actually it'll be a bit more subtle than that, because each iteration
> of the simulation updates all nodes in one time interval, the events
> will not usually show the order of iteration - but, where there are
> any secondary effects, that are related to the order in which the
> nodes are updated, these will always happen the same way, which is my
> concern.

You should have a more precise understanding of the dependence of the variables you taking in consideration before randomizing the series of events your are using for tests.

I suggest you start using PPMCC. If it's close to zero or negative you wouldn't have to mind about it! ;)

Thread

Simple algorithm question - how to reorder a sequence economically Peter Brooks <peter.h.m.brooks@gmail.com> - 2013-05-24 01:14 -0700
  Re: Simple algorithm question - how to reorder a sequence economically Chris Angelico <rosuav@gmail.com> - 2013-05-24 18:37 +1000
  Re: Simple algorithm question - how to reorder a sequence economically Fábio Santos <fabiosantosart@gmail.com> - 2013-05-24 09:47 +0100
  Re: Simple algorithm question - how to reorder a sequence economically Chris Angelico <rosuav@gmail.com> - 2013-05-24 19:11 +1000
    Re: Simple algorithm question - how to reorder a sequence economically duncan smith <buzzard@invalid.invalid> - 2013-05-24 15:33 +0100
  Re: Simple algorithm question - how to reorder a sequence economically Terry Jan Reedy <tjreedy@udel.edu> - 2013-05-24 06:10 -0400
  Re: Simple algorithm question - how to reorder a sequence economically Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-05-24 10:52 +0000
    Re: Simple algorithm question - how to reorder a sequence economically Ned Batchelder <ned@nedbatchelder.com> - 2013-05-24 07:26 -0400
      Re: Simple algorithm question - how to reorder a sequence economically Peter Brooks <peter.h.m.brooks@gmail.com> - 2013-05-24 06:23 -0700
        Re: Simple algorithm question - how to reorder a sequence economically Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-05-24 13:57 +0000
        Re: Simple algorithm question - how to reorder a sequence economically Robert Kern <robert.kern@gmail.com> - 2013-06-12 14:14 +0100
    Re: Simple algorithm question - how to reorder a sequence economically John Ladasky <john_ladasky@sbcglobal.net> - 2013-05-24 10:33 -0700
      Re: Simple algorithm question - how to reorder a sequence economically John Ladasky <john_ladasky@sbcglobal.net> - 2013-05-25 18:25 -0700
        Re: Simple algorithm question - how to reorder a sequence economically Roy Smith <roy@panix.com> - 2013-05-25 21:49 -0400
  RE: Simple algorithm question - how to reorder a sequence economically Carlos Nepomuceno <carlosnepomuceno@outlook.com> - 2013-05-24 18:00 +0300
    Re: Simple algorithm question - how to reorder a sequence economically Peter Brooks <peter.h.m.brooks@gmail.com> - 2013-05-24 12:01 -0700
      RE: Simple algorithm question - how to reorder a sequence economically Carlos Nepomuceno <carlosnepomuceno@outlook.com> - 2013-05-25 00:33 +0300
        Re: Simple algorithm question - how to reorder a sequence economically Peter Brooks <peter.h.m.brooks@gmail.com> - 2013-05-24 17:28 -0700

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