Correlation of intuitionistic fuzzy sets by centroid method

In this paper, we propose a method to calculate the correlation coefficient of intuitionistic fuzzy sets by means of "centroid". This value obtained from our formula tell us not only the strength of relationship between the intuitionistic fuzzy sets, but also whether the intuitionistic fuzzy sets are positively or negatively related. This approach looks better than previous methods which only evaluate the strength of the relation. Furthermore, we extend the "centroid" method to interval-valued intuitionistic fuzzy sets. The value of the correlation coefficient between interval-valued intuitionistic fuzzy sets lies in the interval [-1, 1], as computed from our formula. (C) 2002 Elsevier Science Inc. All rights reserved.