The Average Run Length and Detecting Process Shifts

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Thanks so much for reading our publication. We hope you find it informative and useful. Happy charting and may the data always support your position.


Dr. Bill McNeese
BPI Consulting, LLC

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Comments (4)

  • Raphy BarSeptember 20, 2021 Reply

    I belive thre is a typo error: the mshif is +1sigma and +2sigma.The following exerpt:”The probability of getting a point beyond the mean + 2σ for the shifted process is:a = 1 – NORM.S.DIST(2, TRUE) = .02275″is correct for +1sigma.

    • billSeptember 20, 2021 Reply

      I believe the article is correct.  If a process shifts +1 sigma, the "new" 2 sigma is where the "old" 3 sigma was.  So, you are looking at the area above +2 sigma, which is 0.02275.

  • AnonymousDecember 27, 2021 Reply


  • GerrohardtApril 21, 2022 Reply

    Thanks, good introduction to ARL

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