Ventana software support forum

Hi everybody,

Where I can find information about ecenometric vs system dynamics (sd)? In terms of advantages and disadvantages of sd over econometric model. Thank you in advance.


Regards,
Nadia

Ok.Thank you very much. It really helps me a lot.But what about the farmers net income? Where I can get the info about how to use min function?Thank you in advance.


Nadia.

Hi,

My model as attached. Hope I can get comments and suggestions for improvement for my model. Thank you.


Nadia.

Hye everybody, Why stock become negative? When I try extreme condition test my stock become negative.But, the others variables behave appropriately. Only the stock become negative.Anybody please help me. Is that possible if I attach my model and get comment for improvement in my model. Really need y...

Hi everybody,

It is just a simple question.System dynamics itself has s.I mean the term dynamics. What about system dynamic model? Does it has s or without s?Thank you in advance.


Regards,
Nadia.

Hi everybody, How to use the ramp function?in my sd model, actual data shows that per capita consumption of rice shows a declining trend at 1percent over the year. Therefore, how im going to put in this scenario in my model? is it possible for me to use the ramp function?By the way Im using vensim.T...

Yes.Im using vensim.Thank you so much for the info.

Regards,
Nadia

Hi everybody, How to put delay in our model? Is it we just have to put delay mark in our sketch? For example, in Malaysia, we plant paddy 2 times in a year.We have 2 types of seasons which are main season and off season. The main season is in between 1st August to 28 February. While off season is in...

hi,

Yes, this fraction can be greater than 1. Thank you everybody for your opinion and suggestions.


Regards,
Nadia

Is that means when the fraction is greater than 1 the model has error?

Thank you.

Actually I want to see at what amount of fertiliser that we have to add in order to get maximum yield. This is because the amount of fertiliser subsidy provided by the government is fixed and not enough. Therefore, farmers have to buy extra fertiliser in order to get maximum amount of yield. My equa...

Hi,

Why there is a message said that "warning, at 2010.25 above- fertiliser lookup computing- effects of fertiliser on yield" when I run the model?

Is it because of the error with the fertiliser lookup?

Thank you,

Regards,
nadia

Ok.thank you so much.

ok..thank you so much.

Regards,
Nadia

Hi,

How to avoid negative stock?

Thank you.


Regards,
Nadia

Ok. thank you so much for your suggestion.I'll try to do it again.

Regards,
Nadia

hi,
Yes, because there must be at least one stock for each feedback loop right?

The rice stock model that cannot be simulated due to simultaneous equation as attached.

Hi, Im Nadia. Master's student from Malaysia. Actually sd is really new in Malaysia. No expertise yet in Malaysia. I already try build the model but this can not be run. Is it possible if I attached the model and get the comment from you? This problem is regarding to the rice stock. The inflow for t...

Hi, How I can build the equation of rice stock model? In Malaysia the function of rice rice stock is as the buffer stock for food security but not as stabilizing the price. This is because local production is not enough to afford total demand. Therefore, we have to import rice from other countries. ...

Hi,

Is it possible for me to compare the actual behaviour with the simulated one in vensim?

Thank you in advance.

Regards,
Nadia

Hi

Thank you everybody for your respond.

Hi, How to avoid simultaneous equation? In my model i have rice stock. The rice stock is depends on the local rice production. And the outflow is the demand. Since the local rice production cannot afford the demand, so we have to import. So that the equation for the import=demand-supply. supply=loca...

Hi.
Means that in sd there is no specific method to show that our model is valid? Because in my country sd is still new.
Thank you.

hi.
how to validate the model in sd?

Thank you.