calibration procedure / example

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grle
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Posts: 2
Joined: Tue Jan 09, 2018 9:28 pm
Vensim version: DSS

calibration procedure / example

Post by grle »

Hi,

I am quite new in SD and I am trying to use the method for my PhD. I took over the model from a former colleague. After correcting some equations, I can see my model is off, as it had been manually calibrated for the first "wrong" model. I am now considering the calibration module to give it a try, as there are numerous parameters and a manual one is a waste of time I think. I have read on the forum, the help manual, but this is still not clear.

I defined a payoff, i.e. one of my variable compared to a measurement one (time serie). I just try a parameter that I know would influence the results. and ... I am not exactly sure if something happens. I do not see any changes. I do not see any *.out file. Where am I supposed to find the updated values, if existing?

Any extra documentations, files or simple models with a calibration phase working would be highly appreciated...

Regards,
Greg
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Re: calibration procedure / example

Post by Administrator »

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tomfid
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Re: calibration procedure / example

Post by tomfid »

I think an initial manual calibration is NOT a waste of time; it's very helpful for developing some intuition about what matters and what is plausible. Normally, I set up a simple control panel showing the relevant model-data comparisons and parameters. Then I do the calibration in synthesim. This requires that the model be reasonably fast (at most a few seconds). How many is "numerous"?
grle
Junior Member
Posts: 2
Joined: Tue Jan 09, 2018 9:28 pm
Vensim version: DSS

Re: calibration procedure / example

Post by grle »

Hey Tomfid,

You are correct, manual calibration is a good thing for the reasons you mention. "Waste of time" was not exactly what I meant, but more tedious procedure. The automatic calibration helps to verify if you can get reasonable values of parameters and reproduce the dynamic of the system. In the meantime, I managed to make the calibration work which certainly is a good thing.
Is there a way to load the calibrated parameters into the model afterwards to keep working from there?
Administrator
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Re: calibration procedure / example

Post by Administrator »

The optimization will produce a ".out" file, this can be used as a standard CIN file in Vensim (Model->Simulate, select "Changes", and "Load changes from").
Advice to posters seeking help (it really helps us to help you)
http://www.ventanasystems.co.uk/forum/v ... f=2&t=4391

Units are important!
http://www.bbc.co.uk/news/magazine-27509559
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