To: SYSTEMDY--EKSMTP System Dynamics Ma
From: William Bonnell
Management Services Division
Bldg. 56-4, KP, Mail-24530 (716) 477-7874
Subject: Modeling Soft Variables
Developing system thinking consulting skills is an example of modeling
soft variables that I worked on. Id like to be able to show you the
structural diagram. It shows the logical relationships of variables.
The diagram is the first step. You map out your understanding of the
problem. This may be enough. People gain insight doing this especially
when used as a group process.
After the diagram is built, you have to model the relationships. This
is the artsy part. You can hypothesize the relationships (make em up)
or you can look for natural laws, or statistical inferences. Like it
says in ITHINK(tm) when you open an object, "Place right hand side of
equation here". Often this can be made easier by using generic modeling
templates such as growth, draining, coincident flow, goal seeking, etc.
The graphical input function is most useful for modeling soft
variables. By making a normalized index of one or more variables on the
X axis and sketching a curve, you have a functional relationship
mapping to the Y axis variable of interest.
At this point you can begin to simulate, fix the problems, learn about
the relationships, explore your theory. Getting things to be visible
and open for challenge is necessary for learning.
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Bill Bonnell
kp40.588458@kodako.kodak.com
73323.2112@compuserve.com