The Uniqueness of the Overall Assurance Interval for Epsilon in DEA Models by the Direction Method

The role of non-Archimedean  in the DEA models has been clarified, so that the associatedlinear programs can be infeasible (for the multiplier side) and unbounded (for theenvelopment side) with an unsuitable choice of  . This paper shows that the overallassurance interval for  in DEA models is unique by the concept of extreme directions. Also,it presents an assurance value for  using only simple computations on inputs and outputs ofDMUs.