Pearson’s coefficient between intuitionistic fuzzy sets

The correlation coefficient (Pearson’s r) is one of the most frequently used tools in statistics. In this paper we discuss a correlation coefficient between Atanassov’s intuitionistic fuzzy sets (A-IFSs). We have constructed the coefficient so it provides the strength of the relationship between A-IFSs and also shows if the considered sets are positively or negatively correlated. Next, the proposed correlation coefficient takes into account not only the amount of information related to the A-IFS data (expressed by the membership and non-membership values) but also the reliability of the data expressed by a so-called hesitation margin.