QUERY Structural changes and validity (SD6660)

[SDMAIL Monte Kietpawpan]

Posted by  Monte Kietpawpan <kietpawpan at yahoo.com>

Dear all,
   
  Structual validation is key to the success of model development. 
  However, we have no test to determine whether a given model structure 
  is stable over the time horizon of interest. 
   
  Basic mechanisms may at best represent the "past structures" 
  capable of generating the "past behaviors". No existing validity 
  tests serve to check whether the relationships in the real system 
  will not significantly change in the future--within the time horizon. 
  If the real structure changes, the model of past behavior would 
  lack the ability to generate the future behavior. It is therefore 
  hard believe that SD models are theories, unless the structures 
  of the aspects being modeled are stable.
   
  SD is not effective in dealing with social problems, of which 
  the dynamics of the system structures are not yet predictable. 
  Projection of dynamic behavior, to be successful, calls for the 
  ability to project the dynamics of the structure, the ability that 
  the oracle of Delphi posses.
   
  MK
Posted by  Monte Kietpawpan <kietpawpan at yahoo.com>
posting date  Thu, 4 Oct 2007 02:33:59 -0700 (PDT)