In decision analysis, the background state of information (or background of understanding) is the implicit context within which a decision basis is asserted. In particular, all the distinctions and probability distributions in the basis are asserted within this context. In mathematical notation, the background state of information of a probability distribution is denoted by the symbol E. Different states of information are typically denoted by subscripts (eg, E₁, ..., E_n). When a decision basis is developed using multiple experts (with correspondingly different background states of information), care must be taken to validate all assessments into a single state of information.

See also: Basic Relevance Diagram, Conditional Independence,  Decision Context, Decision Situation, Dependence, Mutual Independence, Pairwise Independence, Pedigree, Related, Relevance and Relevance Diagram.