Fuzzy composite indicators: an application for measuring customer satisfaction

Composite indicators should ideally measuremultidimensional concepts which cannot be captured by a singlevariable. In this paper, we suggest a method based on fuzzy settheory for the construction of a fuzzy synthetic index of a latentphenomenon (e.g. well-being, quality of life, etc.), using a setof manifest variables measured on different scales (quantitative,ordinal and binary). A few criteria for assigning values to themembership function are discussed, as well as criteria fordefining the weights of the variables. For ordinal variables, wepropose a fuzzy quantification method based on the samplingcumulative function and a weighting system which takes intoaccount the relative frequency of each category. An applicationregarding the results of a survey on the users of a contact centeris presented.