REPLY Meaning of Stock/Level (SD6894)

[SDMAIL Stephen Wehrenberg]

Posted by  Stephen Wehrenberg <stephen.wehrenberg at verizon.net>

Alan,

Wouldn't your proscription depend on the purpose of the model?  If the 
purpose is to attempt to predict, soft variables would create the 
problems you assert.  But if the purpose of the model is otherwise, 
perhaps not. 

I have used SD models purely to gain a better understanding of the 
relationships of many of the soft variables you mention (I'm a 
psychologist).  I have also used models to promote a group's common 
understanding of the nature of a problem.  In neither case was the 
purpose of the model not achieved because of the introduction of 
variables  that have no physical property. 

Steve

Stephen B. Wehrenberg, Ph.D.
Posted by  Stephen Wehrenberg <stephen.wehrenberg at verizon.net>
posting date  Wed, 09 Apr 2008 18:40:36 -0400