An assurance interval for the non-Archimedean epsilon in DEA models

This paper clarifies the role of non-Archimedean infinitesimal epsilon in DEA models so that the associated linear programs may be infeasible (for the multiplier side) and unbounded (for the envelopment side) for certain values of epsilon. It is shown that the bound of epsilon proposed by Ali and Seiford (1993) is invalid for feasibility and boundedness of the linear programs. A procedure is presented for determining an assurance interval of epsilon. It is also shown that an assurance value for epsilon can be found using a single linear program.