Multiple runs of a stochastic model

lyndarodwell · Post by **lyndarodwell** » Fri Oct 10, 2003 10:28 am

Hi Tony,
I am using Vensim DSS and trying to run a model with stochastic elements to it. I need to have repeated runs where random distributions change in each run.
How do I do this? I can only find how to change parameters in sensitivity
simulations.

Lynda

Post by **Administrator** » Fri Oct 10, 2003 10:58 am

The easiest way is to change the noise seed for the random number generation and do lots of batch runs (see
http://www.vensim.com/documentation/html/25670.htm for details on how to automate this process using a command file). Basically change the noise seed and save each run under a different name.

Is this what you are after?

Tony.

lyndarodwell · Post by **lyndarodwell** » Fri Oct 10, 2003 11:17 am

That sounds like it might work so long as I can automate it. 100 simulations individually run would drive me crazy. The program can do it automatically can it?

lyndarodwell · Post by **lyndarodwell** » Fri Oct 10, 2003 12:27 pm

Thanks for the idea Tony. I have now entered the noise seed as a constant 's' and can simulate 100 runs through a sensitivity test by varying 's'.
It seems to be doing what I want. Does it sound right to you?

Post by **Administrator** » Fri Oct 10, 2003 12:49 pm

Thats exactly what I would do, so yes, it sounds fine.

Tony.