The DEA approach, a non-parametric mathematical linear programming technique, is the method that has been most commonly used in extant studies to measure the relative efficiency of insurers or, more broadly, decision-making units (DMUs) [7]. In contrast to the traditional DEA approach, which is radial and takes no account of slacks, the SBM model is a non-radial, non-oriented model that deals directly with the input and output slacks of the DMU of interest. The non-radial feature acknowledges the generally non-proportional nature of noticeable deterioration in performance in the real world. The efficiency measure of the SBM model is between 0 and 1. It reports an efficiency score of unity if and only if the DMU concerned is on the frontier of the production possibility set without any input or output slacks. Other desirable properties of the SBM model are: (i) it is unit invariant and monotone decreasing with respect to input and output slacks, (ii) the efficiency score is determined only by consulting the reference-set of the DMU of interest, and (iii) it is not affected by statistics over the whole dataset.