A Reply to Zhu: How Useful or Accurate is This Alternative?
本文回应了朱提出的替代方法，指出其在设定规模效率目标时不准确，因为目标值不在可变规模收益的生产可能性集内，且基于弱有效决策单元导致错误。
How useful or accurate is this alternative?Zhu gives an alternative approach for setting the scale-ef®cient targets for which he claims slight superiority and ®nds a different target for DMU3 as shown in our example.While his approach is de®nitely an alternative to the one we published, it is not accurate and its superiority is a moot point.Firstly the inaccuracy: applying his alternative approach to our 9 DMU example, he comes up with an MPSS max target of (30, 30, 20).But this so-called target value is not in T VRS Ðthe production possibility set for the variable returns to scale model.This can be checked by trying to solve the relevant constraints given by ( 2) on page 61 of Appa and Yue. 1 It is a valid target under the assumption of CRS, but how absurd to set a target for achieving scale ef®ciency on the assumption of constant returns to scale.The reason for this inaccuracy is that in setting scale-ef®cient targets Zhu does not con®ne himself to our set J CRS .DMU3 is weakly ef®cient and therefore must not be in J CRS .The largest or smallest MPSS giving target must be based on ef®cient and not weakly ef®cient DMUs.