A note on Fukuyama (2000)

This brief note discusses Fukuyama’s paper [Fukuyama, H., 2000. Returns to scale and scale elasticity in data envelopment analysis. European Journal of Operational Research 125, 93–112]. We prove that the Proof of Lemma 1 by Fukuyama (2000) is incorrect due to incorrect substitution. In addition, we exemplify our conclusion by a counterexample taken from Fukuyama (2000). Thus all conclusions, based on Lemma 1, of Fukuyama (2000) cannot be reached and are left for further research.