from causal loop to stock and flow

[almoon]

Hi All,

I am looking for some useful resources on how to move from causal loop to stock and flow diagrams, any help?

Thanks

[patrick_at]

Hi almoon,

you should look at your causal loop diagram and try to figure out which variables are stocks because they accumulate (material, people, information...). For example, in the causal loop diagram you posted, obvious stock variables are "staff", "accumulate profit", "students population", "facilities",... If you froze the model, you would need the values of these variables to start the model again. Some variables in your diagram are the flows for these stocks, for example "staff leaving", for other stocks the flows are missing (you have a direct connection from "investment" to "facilities", but investment should increase the rate of new facilities and maybe decrease the decay of old buildings.

I can recommend the book of Sterman "Business Dynamics" for a description of the whole modelling process.