System Dynamics Methodology

[Gene Bellinger]

I folded a new page into WikiSD this morning entitled Systemic Intervention:

http://www.systemdynamics.org/wiki/index.php/Systemic_Intervention

What I really wanted to put up was a page entitled "System Dynamics Methodology" though the shortest one I've been able to find online is about 16 pages long.

Does anyone have a "crisp" and "concise" 1-2 page System Dynamics Methodology I can put on WikiSD. I'm looking for something short though with a bit more meat in it than just a bullet outline.

If you have one could you please send it to me?

thanks & be well,
Gene Bellinger
gene@thefirstdisicpline.org

[Gene Bellinger]

With many thanks to Professor Forrester the System Dynamics Methodology page is now in place.

http://www.systemdynamics.org/wiki/index.php/System_Dynamics_Methodology

be well,
Gene

[Corey Lofdahl]

Just wanted to add a few SD methodology comments. I've always organized my SD studies using the Reference Mode as described by Jorgan Randers' "Guidelines for Model Conceptualization" in _Elements of the SD Method_(1980). Though perhaps this is the 16 page description to which you referred. I use a slightly modified and shortened version:

1. State theory
2. State ancillary theory
3. Define time frame
4. Select 7+/-2 key variables
5. Graph them over time
6. Postulate causality
7. Create model
8. Iterate

I point this out because it seems to me that Jay's second box, "convert description to level and rate equations," is a touch abrupt for beginners, and for me as well. If I'm diving into a tough, inchoate, ill-specified problem domain (aren't they all?), it's nice to have these steps broken down so that you can just follow them like a recipe and make some progress. Jay added a ninth bullet, "Change the system," said as if this is the easiest thing in the world.

Also, when thinking about systemic intervention, I can't help by think about Jay's "Counterintuitive Behavior of Social Systems" (Tech Review, Jan '73, D-4468). There Jay talks about the characteristics of social systems, the consequences of which lead to unintended consequences. This is related to, though different than, descriptions of situations that indicate a system oriented intervention may be necessary or successful.

"First, social systems are inherently insensitive to most policy changes that people select in an effort to alter the behavior of the system. In fact, a social system tends to draw our attention to the very points at which an attempt to intervene will fail."

"A second characteristic of social systems is that all of them seem to have a few sensitive influence points through which the behavior of the system can be changed."

"As a third characteristic of social systems, there is usually a fundamental conflict between the short-term and long-term consequences of a policy change."

These three characteristics sometimes manifest themselves in such subtle ways that they are easy to miss. I learned something recently about unintended policy consequences at a conference: It turns out that in the US Government, there are no policy failures, only intelligence failures. I couldn't tell if the guy was kidding.

Corey

[Geoff McDonnell]

I have often used the Figure 4 Diagram in Aldo Zagonel's interesting paper, which focuses on the link between model and reality and the iterative nature of the process.

Zagonel AA. 2002. Model conceptualization in group model building: A review of the literature exploring the tension between representing reality and negotiating a social order. Proceedings of the 20th International System Dynamics Conference, July 28-August 1, 2002, Palermo, Italy
http://www.systemdynamics.org/conferences/2002/papers/Zagonel1.pdf

[Bill Braun]

Jim Hines version of the Standard Method has served me well.

http://www.core.org.cn/OcwWeb/Sloan-Sch ... /index.htm

then follow "lecture notes".

Bill Braun