We emphasize the distinction between two forms of uncertainty that arise in risk and reliability analyses: (1) that due to the randomness inherent in the system under investigation and (2) that due to the vagueness inherent in the assessor's perception and judgement of that system. It is proposed that whereas the probabilistic approach to the former variety of uncertainty is an appropriate one, the same may not be true of the latter. Through seeking to quantify the imprecision that characterizes our linguistic description of perception and comprehension, fuzzy set theory provides a formal framework for the representation of vagueness. In connection with the second form of uncertainty, fuzzy sets and the associated theory of "possibility" are considered as a basis upon whch to model the imprecision and vagueness attached to the expert judgement of eveht likelihood (e.g. component failure). It is noted that from the perspective of the technical complexity of propagation, the possibilistic treatment of uncertainty compares favorably with the more familiar Bayesian approach.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.