Re: When are SD models appropriate?

Joe Kilbride (
Thu, 1 Dec 94 11:51 CST

Hi Denis, <i.e., Denis Cowan <>

You wrote:
>Not sure what you mean by a system dynamic model ?

I am referring to a computer model of system structure using stocks, flows,
feedback loops. Software typically used to do this includes:
ithink or Stella by High Performance Systems
Vensim by Ventana
PowerSim by ModelData
Dynamo by Pugh-Roberts? I'm not sure
(Forgive me if I've not included someone's favorite or misspelled.)

In Senge's book The Fifth Discipline, he talks about at least two such
system dynamic models (the People Express model and the Hanover Insurance
Claims model) that were subsequently made into Management Flight Simulators
so people could "play" with these models and gain a better understanding of
the system and how to better interact with it.

>My method is based on the assumption that I have no idea what
>the client wants and that it usually take 2 or 3 meetings to get
>a broad understanding of what he/she wants. Is this a system
dynamics model?

Not per my previous description. I am talking about a very specific tool
and asking those who use this tool what request clarification process leads
them and their client to agree upon such an intervention. Would agree with
Denis that it usually takes 2-3 mtgs to develop understanding. Am wondering
what those mtgs are like? How you clarify client requests during this
stage? Lots of things can help, so what are your criteria for deciding SD
models will help the most?

Or do we just create SD models because *we want to* and have found someone
we could talk into it? There has to be more to it than that...

_ ____________________________________________
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