QUERY Simplifying qualitative feed back loops

Jean-Jacques Laublé <jean-jac
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Joined: Fri Mar 29, 2002 3:39 am

QUERY Simplifying qualitative feed back loops

Postby Jean-Jacques Laublé <jean-jac » Tue Nov 13, 2007 8:39 am

Posted by Jean-Jacques Laublé <jean-jacques.lauble@wanadoo.fr>

Hi everybody.

Is there anybody that can tell me where to look (books, papers anything) to find some ideas
about how to increase the qualitative understanding of a stock and flow diagram?

Increase of qualitative understanding means being able to redraw another simpler diagram,
losing a minimum of information from the previous one.

The biggest difficulty is loop understanding.

I usually base my understanding on the survey of critical variables and study the action of
the loops on each of these variables.

There are generally not many such variables, generally variables that summarize possible policies.

I study each loop that affects and is affected by the variable studied individually and note its
polarity, its strength (low, medium, strong) and its delay.

Often you find loops that act the same way, but with a different delay often with an opposite sign,
sometimes loops that acts the same way but with a weaker action, generally sharing common paths.

How is it possible to aggregate some loops, or just to suppress some, so as to simplify the
structure, so as to gain understanding and a higher view of the problem.

Has the problem been studied?

How can this simplification be coupled with an eventual next quantification of the qualitative model?

I know some people will say that there is not substitute for quantification.

Yes, but what if I judge that quantification is much more expensive and that there is no a
priori proof that it will deliver more value, especially if there is a lack of data or if the
situation is moving so quickly that past data are not useful?

Or if I prefer to get some first insights from qualitative analysis before making it quantitative,
to secure the path of modelling?

Or if I judge that my brain understands only the structure of a model, whether qualitative or
quantitative?

Regards.

Jean-Jacques Laublé Eurli Allocar
Posted by Jean-Jacques Laublé <jean-jacques.lauble@wanadoo.fr>
posting date Mon, 12 Nov 2007 18:16:58 +0100
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