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A comparison of some modified confidence intervals based on robust scale estimators for process capability index

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Abstract

This paper aims to compare the performances of modified confidence intervals based on robust scale estimators with classical confidence interval for process capability index (Cp) when the process has a non-normal distribution. The estimated coverage probability and the average width of the confidence intervals were obtained by a Monte-Carlo simulation under different scenarios. Simulation results showed that the modified confidence intervals performed well in terms of coverage probability and average width for all cases. Two real-life numerical examples from industry are analyzed to illustrate the performance and the implementation of the classical and modified confidence intervals for the process capability index (Cp) which also supported the results of the simulation study to some extent.

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Acknowledgements

Authors are grateful to two anonymous referees and editor in chief for their invaluable constructive comments and suggestions, which certainly improved the quality and presentation of the paper greatly.

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Authors and Affiliations

  1. Faculty of Science, Department of Mathematics, The Hashemite University, Al-Zarqa, 13115, Jordan

    Moustafa Omar Ahmed Abu-Shawiesh

  2. Department of Physical Sciences, School of Engineering and Computer Science, Bashundhara, Independent University, Dhaka, 1229, Bangladesh

    Shipra Banik

  3. Department of Mathematics and Statistics, Florida International University, Miami, FL, USA

    B. M. Golam Kibria

  4. Faculty of Science and Arts, Department of Statistics, Bitlis Eren University, Bitlis, 13000, Turkey

    Hayriye Esra Akyüz

Authors
  1. Moustafa Omar Ahmed Abu-Shawiesh
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  2. Shipra Banik
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  3. B. M. Golam Kibria
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  4. Hayriye Esra Akyüz
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Correspondence to Moustafa Omar Ahmed Abu-Shawiesh.

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Abu-Shawiesh, M.O.A., Banik, S., Golam Kibria, B.M. et al. A comparison of some modified confidence intervals based on robust scale estimators for process capability index. Prod. Eng. Res. Devel. 14, 217–229 (2020). https://doi.org/10.1007/s11740-019-00939-7

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