Dear Community,

I have some processes modelled with BPMN process diagram (BPMN 1.X) and I have inserted the Business Simulator Attributes related to the times distributions. My choice has been a Normal Distribution specifying mu and sigma. 

Several times, when I run the simulation the following error appears on different activities:

"A negative value for a randomly distributed attribute was determined for object ... in model ...

To avoid this, please change the distribution parameters"

Mu is major of Sigma. It is not that the cause.

I have tried several possible solutions but without changes. 

Please, can you help me? What should I adjust?

My version of ARIS is 7.2 in an Academic Licence. 





by Ralf Angeli
Posted on Fri, 05/10/2013 - 10:10

Unfortunately a truncated normal distribution is not offered for processing times, so you'll have to change the parameters of the regular normal distribution so that no negative value will be sampled.

You could reduce the value of sigma, in order to reduce the spread of sampled values. Or you could increase the value of mu, in order to move the spread of sampled values away from the set of negative numbers.

Obviously both types of changes mean that you cannot use your original distribution shape and position and this will affect the simulation results. You have to decide which changes will have the smallest effects.


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