Ventana software support forum

I have it set for 1458 simulations. There are 6 variable with 3 levels each. the 3x6 factorial is 729 simulations. I am doing two replications or 1458 simulations. I selected MV so the order of combination should be random.

Hello, I noticed that if I change the order of the independent variables in the senssitivity set up I get different results! Is this by design? if so please explain. See attached model. The dependent variable in question is IRE (∆I/∆Itp). I am using Vensim® PLE Plus for Windows Version 6.4b (x32) Se...

Thanks very much for your reply. It was very helpful!

V/r,
john

I am doing a design of experiment with my model and need to add "pure error" ( i.e., noise) to a dependent variable. The variable is IRE Trend (∆I/∆Itp) in the attached model. Is there a prefered or recomended way to add noise to a variable? a) Multiply by the dependent variabe by a random...

JJ! Thanks for the get vdf idea. I'll give that a try. I actually figured out a solution as well. If you make the seed a variable and set it as a multivariate parameter in the sensitivity analysis, you will get a different seed on each simulation run. I'll add your get vdf to my bag of tricks. Thank...

Tried GET TIME VALUE. Its not supported in PLE+

Any other options?

Correct. I am trying to do many sensitivity runs and would like to use a different seed each time. This will give me a broadly distributed residual error for my data points. Looks like GET TIME VALUE will get different seeds within the simulation run but each run will still be the same. Correct? I n...

Hello,
Is there a way to have a random distribution change on each simulation run?

I am doing a sensitivity analysis and would like to have the random distribution (preferably uniform or normal) change on each run. Can I make the seed random?

Thanks,
john

Sorry ... False Alarm! I restarted the program and it is working fine now.

Simulation seems to work fine. still seems to work fine. However, .vsc files are not loading and or not being saved correctly. Same for .lst files. Model parameters have to be entered each time rather than using saved parameter values. Not sure if i'm doing something wrong. I was able to do this suc...

AWESOME!

Ran a few tests and it seems to be working great. So far I tried up to multivariate five factors with four levels and 500 iterations. No problem. Not sure but it seem to run faster than 6.4a

Just in time for my research deadline.

THANK YOU!

All the best,
john

Is your formula for the Customer 6 order correct?

Customers 6 orders=Drop out sixth order+Sixth order rate

Seem like it should be

Customers 6 orders = Sixth order rate - Drop out sixth order

Hello Tom,
Is there an estimated release date of the new build? Hate to be a pest but I have a research deadline rapidly approaching.

Thx,
john

I see the FP when I increment Degrees of Freedom (Df) from .6 to about .7

Your text file look right. How do fix I load the fix?

That's good news! Your clue about a floating point error made me look at the model closer. I am using "SAMPLE IF TRUE" function for the IRE auxiliary variable. If i manually iterate the constants in the sensitivity analysis, I see a very quick floating point error as the IRE variable trans...

Thanks in advance for taking a look.

Hello,
I have 5 parameters and 3 levels and wan to run a sensitivity analysis using the vector distribution and latin grid. Each time I try to run the analysis, the process stops before completing all of the simulations. The same thing happens even if I make it 2 levels.

Any ideas?

Thanks very much for your help! My tipping point model works great (see attached). Any recommended improvements are welcome.

John

AWESOME!
SAMPLE IF TRUE works! This may be the key to my tipping point problem. Will post my final solution.

Thanks

That sounds exactly like what I need. Unfortunately SAMPLE IF TRUE is not available for PLE+ ( or PLP)

Guess I should have mentioned the version of Vensim I am working with in my original post. Can I create the functionality manually by combining other functions?

Thank you very much. This is a good hint. My challenge now is holding the tipping point once it is reached. 1) Lets say the values for "stock A" are: 1,3,2,4,10,1,2 2) The tipping point =9 3) I used the Max function to "Test" if tipping point was reached: "Test" =MAX (&...

Hello , I am attempting to model the dynamics of a tipping point: 1) Stock A increases then returns to its initial value. 2) If Stock A increase beyond a certain point (tipping point) then it will decrease to a new level = initial value +X Any good ideas / examples? I gave it a try ( see attached) O...