When you view a DynRisk model in “graphical view” mode, you will see a diagram consisting of nodes connected with straight lines. The lines are referred to as “edges”. Each edge has a direction indicated by an arrow. The edges represent dependencies between the various nodes. A diagram consisting of nodes and edges like this is called and “influence diagram”.

We have compared a DynRisk model to a spreadsheet model, where the nodes correspond to the (numerical valued) cells in the spreadsheet. If we try to extend this comparison to edges as well, we immediately realize that in a spreadsheet there are no edges. Although there may be lots of dependencies between the cells in a spreadsheet, this is not reflected visually. Thus, just by looking at a spreadsheet, there is no way you can tell what dependence structure you have between the cells.

In an influence diagram, however, the dependence structure is immediately clear. This is one of the main advantages of such diagrams.

In DynRisk there are basically two kinds of edges:

	• Black edges
	• Gray edges

A black edge simply transfers the output value from one node over to another, while a gray edge transforms the output value before it is sent to the receiving node.