The sensitivity simulation capabilities uses variation in model constants to change output. In some cases it is desirable to have different noise streams in active model variables. To do this use the RANDOM… functions available in Vensim and do sensitivity search on the Constant NOISE SEED or the particular Stream ID you supplied as a parameter to the random function. This will give different noise streams on each simulation. You should use either a VECTOR distribution on NOISE SEED or RANDOM UNIFORM(0,X) where x is large compared to the sample size, e.g., 1 million. (You can actually use any range you wish here but increasing the range will not improve the randomness character because of floating point to integer conversion issues.)
If you are using RANDOM… functions with separate noise stream IDs, you can choose to change only some of those noise streams by changing the seed argument to them. For example is you have:
my price = RANDOM UNIFORM(20,30,MYSEED) ~~|
their price = RANDOM UNIFORM(20,30,0) ~~|
then doing a search over MYSEED will show the results of different values for my price with a consistent (though still random) set of values for their price.
