optimize-calibration

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bahri
Senior Member
Posts: 61
Joined: Wed May 11, 2016 4:43 am
Vensim version: DSS

optimize-calibration

Post by bahri »

Hi,

Does Vensim do a similar process/steps to calibrate a stock and a flow variable?
Shall I am aware something when I calibrate either a stock/flow variable?
Administrator
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Joined: Wed Mar 05, 2003 3:10 am

Re: optimize-calibration

Post by Administrator »

Sorry, I do not understand what you want to do.

Have you looked at the help system for calibration?
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
tomfid
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Re: optimize-calibration

Post by tomfid »

There's no difference, except with respect to Kalman Filtering. https://www.vensim.com/documentation/ref_kalman.htm
bahri
Senior Member
Posts: 61
Joined: Wed May 11, 2016 4:43 am
Vensim version: DSS

Re: optimize-calibration

Post by bahri »

Tom, thanks a lot for your reply.

If we do calibration continuously (maybe 24 hours), does it mean we will get
almost nil payoff?
or
does Vensim absolutely help us to get almost nil payoff?

Could you please explain of how to create Kalman-filter file (*.prm)?
Administrator
Super Administrator
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Re: optimize-calibration

Post by Administrator »

bahri wrote: Wed Aug 01, 2018 8:20 amIf we do calibration continuously (maybe 24 hours), does it mean we will get
almost nil payoff?
or
does Vensim absolutely help us to get almost nil payoff?
It depends on the model you are trying to calibrate. Large models might never calibrate fully.
bahri wrote: Wed Aug 01, 2018 8:20 amCould you please explain of how to create Kalman-filter file (*.prm)?
Have you checked the Vensim help system?
http://www.vensim.com/documentation/ind ... ?23625.htm
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
bahri
Senior Member
Posts: 61
Joined: Wed May 11, 2016 4:43 am
Vensim version: DSS

Re: optimize-calibration

Post by bahri »

I am trying to calibrate a stock model (fluctuated values depend on precipitation) and
I have found it's hard to get fully calibrate.
The model itself contains only less than 35 variables.
tomfid
Administrator
Posts: 3806
Joined: Wed May 24, 2006 4:54 am

Re: optimize-calibration

Post by tomfid »

35 parameters, or 35 variables in total?

If the model doesn't fit the data after you've extensively explored the parameter space, there are some generic possibilities:
- model structure is wrong or incomplete somehow
- data has systematic errors
- noise has moved the system state
bahri
Senior Member
Posts: 61
Joined: Wed May 11, 2016 4:43 am
Vensim version: DSS

Re: optimize-calibration

Post by bahri »

Hi Tom,
after applying Kalman filter, I got a better position.
Thanks.
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