The maximum and minimum number of efficient units in DEA with interval data

In original data envelopment analysis (DEA) models, inputs and outputs are measured by exact values on a ratio scale. Cooper et al. [Manage. Sci. 45 (1999) 597] recently addressed the problem of imprecise data in DEA, in its general form. In this case, units do not have constant efficiency score and their efficiency score depend on the choice of data of units. Therefore, it is attractive to know upper and lower bounds for the number of efficient units. In this paper, we concentrate on DEA with interval data and describe which data settings of units produce the maximum number of efficient units, then we discuss about the minimum number of efficient units.