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Influence Diagram

Closely related to decision trees and often used in conjunction, Influence Diagrams are a summary of information contained in a decision tree. They involve 4 variable types for notation: a decision (a rectangle), chance (an oval), objective (a hexagon), and function (a rounded rectangle). Influence diagrams also use solid lines to denote influence. Their appearance is much like that of a flowchart.

Influence Diagrams show the dependences between variables. This is an important distinction between Influence Diagrams and decision trees. Decisions trees offer much more detail about each possible decision.

Influence Diagram
Typical Uses

If a decision tree is very complex and needs to either be explained to someone or presented, an Influence Diagram is very helpful.

Best Practices
  • Start your tree. Draw a rectangle near the top-left corner of the page; this will be the first node. In this rectangle write the first question or a criterion that leads to a decision.
  • Add to the process. Referencing the decision tree, add more boxes to the page as needed, labeling each. A series of decisions, functions, and chances should lead to an objective.
  • Add connectors. Draw lines between all related boxes with arrowheads indicating the flow of influence. Each box should be connected to at least one line.
  • Verify accuracy. Consult with all stakeholders to verify accuracy.

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