Fuzzy systems approach versus possibility theory approach for representing customers' stated preferences on freight transport services

Everyday companies’ logistic managers have to make the best choice in freight transportation, evaluating alternative services according with their needs. In the context of a wider research project1 that involved a set of companies localized in the Mechanic district of Northern Vicenza, we investigated, by a “SP” type survey, the propensity towards changing transportation service, focusing on some significant forms of transportation in terms of frequency and quantity of goods transported. The propensity for change, as a function of the choice factors, appeared to be a significant index for directing the decisions of the transport services providers towards options appreciated by users and, at the same time, compatible with future scenarios of the supply system. The objective of the research described in this paper is to find out a ranking of preference on transportation hypothetical alternatives proposed, with the necessity to maintain in the analysis phase the uncertainty associated with evaluations of the semantic type expressed by interviewees. In order to achieve this objective we used two different approaches: the first based on fuzzy sets and possibility theory (only descriptive approach) and the second based on fuzzy systems methodologies (descriptive and interpretative approach).