A decision tree is a graphical and mathematical representation of a decision problem. A decision tree is a connected tree with two types of nodes—decision and chance—and two types of branches between nodes—probabilistic (emanating from a chance node) and alternative (emanating from a decision node). Decision trees are well-defined mathematical structures that can be evaluated to produce a recommended course of action and to answer certain probabilistic inference questions. Decision trees are particularly useful for representing and evaluating asymmetric decision problems; however, they can be easily misused, because they do not explicitly represent dependencies among decision elements.

See also: Conditional Dependence, Decision Basis, Decision Variable, Dependence, Relevance Diagram and Uncertain Variable.