Posted by
Phil Henshaw-2 on
Jun 29, 2007; 11:57pm
URL: http://friam.383.s1.nabble.com/Article-on-Epstein-tp524125p524152.html
The point to me of 'varying the parameters' of the model is to better
read the fine detail of the physical subject. The model is just
information, not the thing you're trying to understand that is doing the
actual behaving. You can watch the fine detail of how physical systems
work a lot better if there is a little consistent 'discrepancy' in your
model, if you can see it's artificiality, and that difference tends to
be well hidden if your parameters are adjusted in a way intended to hide
the difference.
Phil Henshaw ????.?? ? `?.????
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-----Original Message-----
From:
[hidden email] [mailto:
[hidden email]] On
Behalf Of Douglas Roberts
Sent: Wednesday, June 27, 2007 1:04 PM
To: The Friday Morning Applied Complexity Coffee Group
Subject: Re: [FRIAM] Article on Epstein
That's what an experimental design is for. Without a plan to rationally
vary parameters of the simulation, there is no hope to determine cause
and effect relationships. A good experimental design will define a
series of parameter sweep runs, the results of which can then be
analyzed.
--Doug
--
Doug Roberts, RTI International
droberts at rti.org
doug at parrot-farm.net
505-455-7333 - Office
505-670-8195 - Cell
On 6/27/07, Richard Harris <rich at redfish.com> wrote:
Well, sitting here in the peanut gallery, I think one of the virtues of
small, minimalist models is that they retain at least the option of
having some explanatory value.
I've seen too many instances where people naively try to capture as much
of reality as they percieve in their models, and the only result is a
muddled mess which has zero explanatory value. Even if its not a muddled
mess, and the modeler has avoided making too many arbitrary choices, you
still have to contend with the bounded rationality and understanding of
your audience.
I've seen models which could require hundreds of pages to fully describe
and required massive supercomputers to run. At the end of they day, if
you can't explain something, what's the point?
Rich
I've seen too many occasions when a
Douglas Roberts wrote:
> Josh presented this work to us at our of our NIH MIDAS meetings not
> too long ago. Interesting stuff, but I frankly don't see what all the
> FRIAMers are so agog about. We've all known for a while that
> interesting behaviors can be observed from even the most simple A-Life
> CA simulations (note that is did not use the word "emerge" once in the
> above sentence. Up until this point, that is).
>
> What befuddles me is how much 'complexity scientists' seem to get off
> on how simple simulations can sometimes produce interesting results,
> rather than getting sufficiently cranked up to write *really* big,
> *really* complex societal models, and to then use them to do *really*
> big and complex simulation studies.
>
> This is not meant to imply any criticism against Josh's work -- it is
> quite interesting, and he is a very good presenter. It's just that
> after I see a set of simulation results for a simple simulation of a
> very simple artificial society, it makes me want to see what a more
> realistic, higher resolution one can do.
>
> I understand Josh's motivations for doing simple simulations. As he
> states in the article, "the trick [was] to get a lot /out/, while
> putting in as little as possible", which is cool, sure. To me,
> however it's all about putting as much in as can be rationally
> justified, and then turning the crank to see what pops out.
>
> Michael A: I agree, this thread would make an interesting WedTech
topic.
>
> --Doug
>
> --
> Doug Roberts, RTI International
> droberts at rti.org <mailto:droberts at rti.org> <mailto:droberts at rti.org>
> doug at parrot-farm.net <mailto:doug at parrot-farm.net>
> 505-455-7333 - Office
> 505-670-8195 - Cell
>
> On 6/27/07, *Michael Agar* <magar at anth.umd.edu
> <mailto:magar at anth.umd.edu <mailto:magar at anth.umd.edu> >> wrote:
>
> Good Lord. A shocking line to encounter on arrival in a Florida
> motel.
>
> (That might be a way to start a Carl Hiassen mystery.)
>
> Probably the most interesting things that go on in workshops for
> social/behavioral researchers who know a lot about their area but
> little
> about complexity/ABM is in the discussion space between domain
> knowledge
> and the concept of an ABM. Don't know what to call it, but it's
got
> something to do with clarity and creativity that feeds back into
their
> domain.
>
> This thread would make an interesting Wedtech conversation.
>
> Mike
>
>
> >>> robert at holmesacosta.com <mailto:robert at holmesacosta.com>
> 06/26/07 7:24 PM >>>
> Good question - an explanation that's grounded in actual field
> research
> I
> guess.
>
> IMHO, an ABM can never offer an explanation for a social
> behaviour. All
> it
> can ever do (and I'm not being dismissive, I think this is
> important) is
> offer a suggestion for an explanation that can subsequently be
> confirmed
> or
> denied by real social research/anthropology/enthnological field
> research
> program.
>
> I don't think this is a particularly strong claim. The logic
> behind the
> a
> sugarscape or Netlogo style ABM seems to be (i) apply some micro
> rules
> to
> checkers running round a checker board, (ii) generate an
unexpected
> macro
> behaviour, (iii) offer the micro rules as an explanation of the
macro
> rules
> then (iv) claim that this checker-board behaviour is analagous to
> behaviour
> of real people/animals/companies/other real world entities.
>
> Step (i) through (iii) are OK (though most ABM papers I see aren't
as
> upfront about the many-to-one nature of the explanation as Carl is
in
> his
> email) but (iv) strikes me as a bit of a stretch; certainly I'd
like
> more
> than vague assurances from the researcher that yes it's valid,
honest.
> It
> doesn't strike me as unreasonable to ask for some evidence that
> the leap
> in
> (iv) is reasonable. But how often do we see that in the
> literature? As I
> suggest above, there's plenty of social research techniques that
could
> generate that evidence. But I get the impression that the detailed
> comparison of model with reality that you get in (say) the
Ancestral
> Pueblo
> study is the exception rather than the rule.
>
> And this is why we need more Mike Agars in this world.
>
> Robert
>
>
>
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