Multicriteria Evaluation in a Fuzzy Environment: The Naiade Method

Since the complexity of environmental problems is high, there is a clear need for models offering a comprehensible and operational representation of a real-world environmental system. Qualitative aspects are hard to deal with in traditional models and therefore there is a clear need for methods that are able to take into account information of a “mixed” type (both qualitative and quantitative measurements). Traditional qualitative multichteria approaches take into consideration the case where information on an ordinal scale is present. A problem, related to all multicriteria methods that try to take mixed information into account is the problem of equivalence of the procedures used in standardising the various evaluations of the performance of alternatives according to different criteria. Another problem related to the available information concerns the uncertainty (stochastic and/or fuzzy) contained in this information. Therefore, the combination of different levels of measurement with different types of uncertainty has to be considered as an important research issue in multicriteria evaluation.