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.