A prototype decision support system (DSS) that directly addresses the
nonstochastic uncertainties of an oligopolistic environment is describ
ed. The DSS evaluates price and advertising decisions in the light of
imperfect judgmental knowledge about the price and advertising decisio
ns of competitors in an oligopolistic environment. Traditional econome
tric forecasting methods used to develop the existing system are maint
ained, but the theory of fuzzy sets equips the models with direct asse
ssment of nonstochastic uncertainty. In addition to parameterizing the
econometric equations, the decisionmaker assesses his or her level of
knowledge regarding the fuzzy quantities. These assessments are refle
cted directly in the output of the enhanced DSS. Using Zadeh's ''exten
sion principle'' and the alpha-level sets representation of fuzzy sets
, a practical implementation of the decision support system is achieve
d and exercised for the purpose of describing the benefits of sensitiv
ity analysis.