Exogenous data in transportation model

[Saha]

Hi
I have formed a model for transportation. I checked the model and it says that it is ok. I run the model and I get some errors.
It is really appreciated if you help me with this 3 issues:
1. My exogenous data is GDPPRate which is the growth type based on the time (time series). I could not define it as a lookup data. the error was: GDPPRate is an special variable and can not be used as a normal variable.
2. Then I imported the variable data by a .dat file so that I could sketch it's graph but model does not continue to work and calculate the other variables. The error is: 'GDPPRate' and perhaps other exogenous variables need to specify a file to be read.
3. At the end, I introduced it as a time based equation to the model. I do not see the previous errors but still the other variables' equations do not run and model does not work, that's why it gives floating point error. It is because the variables do not be computed correctly and remain zero.
Would you please help me with it.
Thanks

[Administrator]

You cannot use exogenous data in Vensim PLE.

If you need any more help, you'll need to upload the model. It's impossible to help with the description you are giving.

[tomfid]

I could not define it as a lookup data. the error was: GDPPRate is an special variable and can not be used as a normal variable.

This sounds like an error in lookup usage. See the help system User Guide chapter, https://vensim.com/documentation/usr08.html, or the tutorial video https://vensim.com/lookups-in-vensim/.

Standard usage is:

gdplookup = { define a vector of points }
gdp = gdplookup( time/unit time )

The normalization by /unit time isn't strictly necessary, but suppresses a unit warning.

If you just write
gdp = gdplookup
you will get the 'can't be used as a normal variable' error.

Alternatively you can use an auxiliary and WITH LOOKUP, https://www.vensim.com/documentation/fn ... ookup.html.

[Saha]

Hi
I appreciate your response. I used the "as Graph" tool to define the GDP variable. I do not find the with lookup function anywhere in my program. Do I need to change the unit of GDP in the unit box? I did it but couldn't help. May I send the model to you please?
Thanks

[Saha]

By the way, my Vensim is Vensim.PLE.v7 if it helps.

[Saha]

Thank you. I found with lookup function and I fixed the problem.

[Saha]

Hi
I need to use stats tools to evaluate me real estimated variables with the real ones. I do not find stats tools! I would like to have R square in my graph. can I have it?
Please help me.
Saha

[Saha]

Hi
I need to use stats tools to evaluate me real estimated variables with the real ones. I do not find stats tools! I would like to have R square in my graph. can I have it?
Please help me.
Saha

[tomfid]

PLE doesn't include the stats tool unfortunately. You could generate a table and copy/paste to Excel or something for the comparison.