systems or reference modes?

[Bruce Campbell]

In an earlier post Andrew Jones wrote, in part, that "It is well
accepted that the "model the system" trap is a particularly nasty one".
Ive come accross anecdotal evidence of this on a number of occasions
and have been guilty of it myself. It is an easy trap to fall into when
modelling with people who are very new to SD - it seems so easy to "just
model everything so we can see whats happening". Keeping people
focussed on the purpose of the model is NOT easy.

My question: Does anyone know of discussion of this phenomenon in the
literature, as this topic fits very nicely into my thesis.

Thanks in advance

Bruce Campbell

--
Bruce Campbell
Joint Research Centre for Advanced Systems Engineering
Macquarie University 2109
Australia

E-mail: Bruce.Campbell@mq.edu.au
Ph: +61 2 9850 9107
Fax: +61 2 9850 9102

[George Richardson]

Bruce Campbell asked if there is any literature on modeling problems vs.
modeling systems. Id say the first place a discussion of these issues
appears is in Jorgen Randerss thesis done at MIT around 1974. I dont
have here at home the exact cite, but you could find it in Randerss
Elements of the Systems Dynamics Method (now published by Productivity
Press) which has a lovely paper based on that thesis called Guidelines for
Model Conceptualization.

...GPR

-----------------------------------------------------------------------
George P. Richardson G.P.Richardson@Albany.edu
Rockefeller College of Public Affairs and Policy Phone: 518-442-3859
University at Albany - SUNY, Albany, NY 12222 Fax: 518-442-3398
http://cnsvax.albany.edu/~gr383/
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[Andrew Jones]

Dear SD colleagues:

Several weeks ago, I asked to see SD models of forests and forest product
economies. Several of you were quite generous with your work (Jim Thompson
in particular). Thank you.

Along the way, Jim Hines gently chided me for describing a modeling project
by the general system it addresses. He asked, "Drew: Shouldnt you have
specified the reference mode(s) of interest to the project?" So here is
more background:

The Sustainability Institute is investigating the structures that create
three behavior modes of resource-based commodities. We want to know why:
1. their price tends to oscillate
2. they are managed unsustainably (their regenerative capacity erodes over
time)
3. the people who work at harvesting or extracting the resource tend to
live in poverty

But Jims correction brings up another, more general point. Are we too
often guilty of describing our work using systems as opposed to dynamics or
problems, as Jim suggests? Does it matter? It is well accepted that the
"model the system" trap is a particularly nasty one, but does the same
lesson apply to describing ones work?

Drew Jones
apjones@cheta.net

Andrew Jones w:(828) 236-0884
118 Coleman Ave. h:(828) 252-1266
Asheville, NC 28801 e: apjones@cheta.net
(Backup area code -- 704)

[Jim Hines]

Drews more specific statement of the forest problem should serve as an
example for us all. There are several ways to get specific, reference
modes are one of the best.

Drew asks: "It is well accepted that the "model the system" trap is a
particularly nasty one, but does the same lesson apply to describing
ones work?"

IMHO: Absolutely. Being specific about the aspects of the system that
are of concern does three things: First, it helps folks to know whether
or not they have something to contribute to your work. Second, by being
specific you help everyone on the list understand how system dynamics
might shed light on your issue area. And, finally, you help all of us
learn how to better take one of the most important steps in SD --
figuring out what to focus on.

Regards,
Jim Hines
MIT and LeapTec
From: Jim Hines <jimhines@interserv.com>