Hey, im new to vensim. I cant seem to figure out how to make this stock and flow diagram work..
I would really appreciate som tips/help!
Stocks and flows
Stocks and flows
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- Tommis s and f.mdl
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Re: Stocks and flows
I think it would be good to start by resolving the unit errors, because some of them suggest conceptual problems in a few equations.
In particular,
I'm not sure what's going on here, but this is integrating the average of the inflow and outflow, both as positive values. Probably this should just be INTEG( surveys in executions - Surveys executed, 100 ). Generally your INTEG expression (i.e. stocks) should only be summing the inflows (added) & outflows (subtracted).
Not sure what the "1-0.8" here means, but guessing that this should be made a separate named parameter, like
cancellation rate = 0.2 ~ fraction/year There are several other parameters buried in equations that should be made into separate named variables.
In particular,
Code: Select all
Surveys in execution =
INTEG( ( surveys in executions
+ Surveys executed )
/ 2,
100)
Code: Select all
Cancelled =
Surveys in aqusition
* ( 1
- 0.8)
cancellation rate = 0.2 ~ fraction/year There are several other parameters buried in equations that should be made into separate named variables.
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Re: Stocks and flows
Thank you for you're reply!