REPLY Models, Problems and Systems (SD7026)

[SDMAIL Jack Homer]

Posted by  "Jack Homer" <jhomer at comcast.net>

Jay Forrest writes:

"Discussions with clients who have used SD suggest to me that a 
significant portion of their failure to pursue SD over time is
that they tend to find SD answers don't work over time - which is 
ultimately IMO a failure of them to appreciate the limits of the model. 
And please note...this is not a plea for modeling the system but rather 
recognizing the system - a case IMO where causal loop diagramming or 
even clever extraneous variables shown but not included in the model 
might be helpful. It seems critical that the client be given (or develop 
in the client) an appropriate appreciation of the limits of the model."

"It seems to me that, as a professional, the modeler/facilitator has an 
ethical responsibility to strive to recognize the
key dynamics of the system and to guide the client to a broader 
perspective of the system under study when appropriate."

These are both important points.  The way I like to put them together in 
practice is this:  First, during the conceptualization stage, I guide 
the client toward a broader view of their issue, going beyond the usual 
organizational boundaries to include more actors and levels of influence 
than are typically considered and over a longer time frame.  The result 
of this exploration is a rich causal-loop diagram, a "big picture".  
But, for a variety of practical reasons, the formal simulation model 
(though still having its share of dynamic complexity) often ends up 
focusing on only a portion of the big picture, namely those aspects that 
spark the response, "These are the things we most need to understand 
right now for our next steps in planning or consensus building or 
decision making."  But later, as the lessons of the somewhat narrower 
formal model are being absorbed, the modeler needs to remind the client 
again of the bigger picture.  This review of the bigger picture may 
suggest moving on to further phases of formal modeling, or, if not that, 
at the least a discussion of how the findings of the formal model should 
be qualified based on the broader context that surrounds it.

This is an approach I have taken frequently in recent years, especially 
with highly multidimensional and multiscale public health issues; for 
example, in studies of antibiotic resistance, diabetes, obesity, and 
most recently, cardiovascular disease.

Jack Homer
Posted by  "Jack Homer" <jhomer at comcast.net>
posting date  Sat, 10 May 2008 23:22:34 -0400