# Normal distribution and failed simulation

First, I'd like to thanks for providing such a great tool.

In the attached model, I had a problem running simulation when I set parameters for the normal distribution. For instance, when I set the processing time of "Pack the pizza" activity with mean = 3 and sd = 1. The system showed "the simulation has failed. Please ensure that your model is compliant to the BPMN2.0 standard and that it is supported by the simulation" However, when I changed it to the following settings (mean = 5/sd=1 or mean =1/sd=0.1), the model worked well. Since I couldn't find any detailed error logs for the runtime operation, can you please check what the specific problem is? My assumption is that under the normal distribution of mean =3 and sd=1, there is a possibility of generating a negative value (P(X<=0) = 0.0013 according to http://www.mathportal.org/calculators/statistics-calculator/normal-distribution-calculator.php), which in turn causes problems. If this is the case, what would be your suggestion to model a distribution with larger variances? Thank you for your help in advance. Much appreciated!

Dear Alder,

We will analyze this issue. As soon as possible, we will write back.

Regards

Dear Alder,

After our analysis. you are correct. Simulation fails because the normal distribution generate negative values during the time. Our recommendation is to use a truncated normal distribution with a minimum value very small or zero to avoid negative values.

Regards

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