Application of Fuzzy System in Psychological Tests: Optimize the Number of Questions for WHOQOL-BREF

The WHOQOL-BREF is one of the best known questionnaires for measuring the quality of life. It is currently available in more than 40 languages and has been used frequently in cross-cultural comparison studies on subjective well-being and quality of life studies. Some research shows that due to certaincultural biases Iranian respondentshave no tendency or willingness to responding some questions, more specially, question 21, in WHOQOL-BREF. The main aim of the current research was to use the ability and flexibility of fuzzy systems to analyse the WHOQOL-BREF questions to reduce some unclear or doubtful questions. A fuzzy system model proposes to diminish the errors that produce ambiguous concepts by not responding to certain biased questions.The WHOQOL-BREEquestionnaire was analyzed and both the traditional model and the fuzzy model analyses were compared for results using fuzzy systems.As a result, question 21 was removed from the WHOQOL-BREF questionnaire used by the fuzzy system.