In decision analysis, a basic relevance diagram is a decision relevance diagram that represents the original formulation of a decision—prior to any manipulations—and, thus, constitutes the decision basis. In particular, all the probability distributions in a basic relevance diagram must be assessed rather than derived (although this assessment may have been obtained by first developing and manipulating a corresponding knowledge map) and must have clear pedigrees. Often, but not always, the distinctions captured in a basic relevance diagram (eg, alternatives, decision variables, outcomes, uncertain variables) have physical interpretations that allow asking (and answering) meaningful value of control questions.

See also: Relevance Diagram.