Experience shows that the cost of producing one chocolate bar varies between 20 and 40 cents with 30 cents as the most likely cost. The total production cost is of course the product of the number of chocolate bars we produce and the cost pr bar. Now, the question is: Where do we enter the cost pr. bar? There are two possibilities: The perhaps most obvious thing would be to add another node and call it something like “Production cost pr. bar”. We could then add an edge from this new node to the “Production cost” node. A more compact solution would be to hide the “Production cost pr. bar” inside the “Production cost” node as a “local value”. The actual output value of the node should combine this local value with the input from the “Number of chocolate bars” node. Since we do not care so much about the “Production cost pr. bar”, we will use this approach here.

Double-click on the “Production cost” node.

In the “Identity” view, enter “$” in the “Unit” field, and then go to the “Distribution” view. 

Select the “Normal” distribution, and enter the following numbers in the parameter fields:

a) 0.2

b)
0.3

b)
0.4

Note that in this case we just use 1 in the “L.Fact.” field, and insert the actual fractiles directly into the (a), (b) and (c) fields. Thus, we are using the absolute uncertainty approach in this case. Make sure the “Include stochastic value” checkbox is checked.