Not at all dumb/boring.
I can think of two ways to do a Monte Carlo with a lognormal distribution.
Assuming your equation is:
z = EXP( mean_ln_x + RANDOM NORMAL( -6,6,0,stdev_ln_x,seed ))
1.
You can make the seed parameter a VECTOR input in the sensitivity setup. Or, use a seed of 0 and vary the NOISE SEED. https://www.vensim.com/documentation/in ... e_seed.htm
2.
Separate z back into its components:
z = EXP( mean_ln_x + normal_variation)
normal_variation = NORMAL( -6,6,0,stdev_ln_x,seed ) {i.e. set this in your sensitivity setup}
Lognormal in Vensim
Re: Lognormal in Vensim
/*
Advice to posters (it really helps us to help you)
http://www.ventanasystems.co.uk/forum/v ... f=2&t=4391
Blog: http://blog.metasd.com
Model library: http://models.metasd.com
Bookmarks: http://delicious.com/tomfid/SystemDynamics
*/
Advice to posters (it really helps us to help you)
http://www.ventanasystems.co.uk/forum/v ... f=2&t=4391
Blog: http://blog.metasd.com
Model library: http://models.metasd.com
Bookmarks: http://delicious.com/tomfid/SystemDynamics
*/