Scala di voto e insiemi sfocati per valutare la didattica

The evaluation of teaching staff by students is often carried out with a questionnaire containing items which ask respondents to indicate their agreement with statements using a five-point Likert scale. To obtain a numeric value on a scale ranging from zero to ten, two possible strategies are presented: the easier traditional procedure and the fuzzy inferential system. The distributions of the numerical values attributable to the Likert scale were derived from the (empirical) data obtained through the analysis of a survey aimed at gathering the opinions (about those values) of the students attending the first year of the Faculty of Economics in Modena. The analysis showed that values on the scale ranging from zero to ten depended on the following: how the question was asked and which terms defined the five categories; the question itself; the kind of course; the intensity level of the Likert scale. A fuzzy inferential system was set up, using the empirical distributions derived form the survey, to obtain the global evaluation of teaching activity. This system was applied to the data of the official survey of the Faculty of Economics. The resulting crisp values were compared from those obtained assigning two, four, six, eight, and ten to the five-point Likert scale, respectively. The fuzzy inferential system yielded scores greater than the others, on the average, by one half.