The principles, steps, and symbols in building influence charts

 When building an influence charts you start with the outcome measure. To decide which variable this is, ask what single variable the decision maker will use to measure the success of a plan of action.

 Decompose the outcome measure into a small set of variables that determine it directly. Each of these influencing variables should be independent of the other, and together they should be sufficient to determine the result.

 Take each variable in turn and repeat this process of decomposition. For each variable, and ask, “What do I need to know to determine?”

 Identify input data and decisions as they arise.

 Make sure that each variable appears only once in the diagram.

 Highlight special types of elements with consistent symbols. For example, use squares for decision variables and double circles for random variables (Baker, 2009).