A correlation coefficient for intuitionistic fuzzy sets

Intuitionistic fuzzy sets are a generalization of the ordinary fuzzy sets in which we have both a membership function mu and a nonmembership function v. In this article we consider the problem of defining a correlation coefficient between two intuitionistic fuzzy sets. We show that by interpreting an intuitionistic fuzzy set as an ensemble of ordinary fuzzy sets we are able to derive a simple, intuitively satisfying correlation coefficient between two intuitionistic fuzzy sets. We show the reasonableness of the results obtained by examining several test cases. (C) 2004 Wiley Periodicals, Inc.