Ordinal scales and fuzzy set systems to measure agreement: An application to the evaluation of teaching activity

Student evaluation of university teaching activity is now compulsory in Italy and a research group of the Italian Ministry of Instruction, University, and Research proposed a questionnaire with items based on the four-point Likert scale and a traditional item-by-item analysis for the evaluation of classrooms, work load, course organization, lectures, and teaching aids. Three split-ballot experiments were carried out to test the differences between the four-point and five-point Likert scale. The traditional analysis is compared with the results of the fuzzy system set up to achieve the same purposes. The fuzzy system yielded scores that proved to be generally higher but sometimes also lower than those obtained using the five- or four-point Likert scale. Furthermore, an extension of standard procedures of the fuzzy system is suggested to obtain a fuzzy item-by-item analysis, thereby increasing the possibility of their use in social sciences.