A note on Cpk index estimation using fuzzy numbers

@article{Hong2004ANO,
  title={A note on Cpk index estimation using fuzzy numbers},
  author={Dug Hun Hong},
  journal={European Journal of Operational Research},
  year={2004},
  volume={158},
  pages={529-532}
}
Recently, Lee [Eur. J. Oper. Res. 129 (2001) 682] calculated standard deviation of fuzzy numbers in order to obtain the membership function of the process capacity index Cpk. In this note, we show that his result is not valid. 2003 Elsevier B.V. All rights reserved.