Unit measure

Not to be confused with Unit of measurement.

Unit measure is an axiom of probability theory^[1] that states that the probability of the entire sample space is equal to one (unity); that is, P(S)=1 where S is the sample space. Loosely speaking, it means that S must be chosen so that when the experiment is performed, something happens. The term measure here refers to the measure-theoretic approach to probability.

Violations of unit measure have been reported in arguments about the outcomes of events^[2][3] under which events acquire "probabilities" that are not the probabilities of probability theory. In situations such as these the term "probability" serves as a false premise to the associated argument.

See also

• Overround, the amount by which the sum of the implied probabilities of a book exceeds 100%