Monitoring process variation using modified EWMA

‬Saghir, Aamir‭;Aslam, Muhammad‭;Faraz, Alireza‭;Ahmad, Liaquat‭;Heuchenne, Cédric
(2020) Quality and Reliability Engineering International — Vol. 36, n° 1, p. 328-339 (2020)

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Authors
  • ‬Saghir, Aamir‭
    Author
  • Aslam, Muhammad‭
    Author
  • Faraz, Alireza‭
    Author
  • Ahmad, Liaquat‭
    Author
  • Author
Abstract
A‭ ‬new‭ ‬control‭ ‬chart,‭ ‬namely,‭ ‬modified‭ ‬exponentially‭ ‬weighted‭ ‬moving‭ ‬average (EWMA)‭ ‬control‭ ‬chart,‭ ‬for‭ ‬monitoring‭ ‬the‭ ‬process‭ ‬variance‭ ‬is‭ ‬introduced‭ ‬in this‭ ‬work‭ ‬by‭ ‬following‭ ‬the‭ ‬recommendations‭ ‬of‭ ‬Khan‭ ‬et‭ ‬al. The‭ ‬proposed control‭ ‬chart‭ ‬deduces‭ ‬the‭ ‬existing‭ ‬charts‭ ‬to‭ ‬be‭ ‬its‭ ‬special‭ ‬cases.‭ ‬The‭ ‬necessary coefficients,‭ ‬which‭ ‬are‭ ‬required‭ ‬for‭ ‬the‭ ‬construction‭ ‬of‭ ‬modified‭ ‬EWMA‭ ‬chart, are‭ ‬determined‭ ‬for‭ ‬various‭ ‬choices‭ ‬of‭ ‬sample‭ ‬sizes‭ ‬and‭ ‬smoothing‭ ‬constants. The‭ ‬performance‭ ‬of‭ ‬the‭ ‬proposed‭ ‬modified‭ ‬EWMA‭ ‬is‭ ‬evaluated‭ ‬in‭ ‬terms‭ ‬of its‭ ‬run‭ ‬length‭ ‬(RL)‭ ‬characteristics‭ ‬such‭ ‬as‭ ‬average‭ ‬RL‭ ‬and‭ ‬standard‭ ‬deviation of‭ ‬RL.‭ ‬The‭ ‬efficiency‭ ‬of‭ ‬the‭ ‬modified‭ ‬EWMA‭ ‬chart‭ ‬is‭ ‬investigated‭ ‬and‭ ‬compared‭ ‬with‭ ‬some‭ ‬existing‭ ‬control‭ ‬charts.‭ ‬The‭ ‬comparison‭ ‬reveals‭ ‬the‭ ‬superiority‭ ‬of‭ ‬proposal‭ ‬as‭ ‬compared‭ ‬with‭ ‬other‭ ‬control‭ ‬charts‭ ‬in‭ ‬terms‭ ‬of‭ ‬early detection‭ ‬of‭ ‬shift‭ ‬in‭ ‬process‭ ‬variation.‭ ‬The‭ ‬application‭ ‬of‭ ‬the‭ ‬proposal‭ ‬is‭ ‬also demonstrated‭ ‬using‭ ‬a‭ ‬real‭-life‭ ‬dataset.
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Citations

‬Saghir, A., Aslam, M., Faraz, A., Ahmad, L., & Heuchenne, C. (2020). Monitoring process variation using modified EWMA. Quality and Reliability Engineering International, 36(1), 328-339. https://doi.org/10.1002/qre.2576 (Original work published 2020)