More Simultaneous Equations

[karankhosla]

Greetings!

I seem to be having more problems....

Attached is a management consultancy problem (Coyle, Practical Approach to SD, P.157)

1. I get simultaneous equations (problem areas marked in red) if I use the initial state / level values given in the problem.

2. I also get simultaneous equations if try and start the problem in steady state! I always try to initialize the steady state in the same manner as the Vensim Modeling Guide suggests (Chapter 5). Wilson (at Vensim) had previously suggested inputting a steady state value instead of a formula, but how and why should that make a difference?

I apologize for bothering you with this, but I really do need to understand why I am making these mistakes.

Best.

Karan

[karankhosla]

One possible solution since I cannot use SMOOTH, could be that I use SMOOTHI and give an initial value to the "average recruitment rate".

[LAUJJL]

Hi Karan

It is true that there was a conceptual problem with that model, and things where not very clear.

I join you 4 models, three are only diagram, eventually with the dimensions, and the last one is a complete model with the equation. It is by necessity slightly different than what was exposed in the book to solve the conceptual difficulty.
The models are unfortunately in French, I do not remember why I made some models in French and some in English.
The two diagrams, consultants_list and consultants_Q have
several interrogation points, and I supposte that it is where the problem was.
I made these models from September to November 2007.
Regards.
JJ

[Edited on 22-5-2009 by LAUJJL]

[karankhosla]

JJ - Merci beacoup, vous êtes très gentil!