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Theory on SPC control limits

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  • #32655

    Michael Schlueter
    Participant

    Hi,
    The constants we use with SPC to estimate control limits were calculated by Herrmann Otto Hartley, as far as I know. Does anybody know, where I can find information about the theory behind?
    Hartley is honored at http://stat.tamu.edu/index.html ; unfortunately I couldn’t find out more details there.
    Thanks in advance, Michael Schlueter

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    #87457

    Eileen
    Participant

    Michael,
    The values of A2 for the average chart are based on the distribution of the average ranges(d2). A2 is equal to 3/[d2 *(Sqrt n )].Various articles exist for the development of d2.
    1. Journal of Amer. Stat.Assoc. (JASA) – Volume LIII -1958, p. 548 by A. J. Duncan.
    2. Industrial Quality Control – Volume XI No. 5 – Feb. 1955-A.J. Duncan.
    You can also check “Quality Control and Industrial Statistics” by Acheson J. Duncan or “Understanding Statistical Process Control” by Wheeler and Chambers.
    Eileen, Quality Disciplines
     
     

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    #87458

    Michael Schlueter
    Participant

    Thanks Eileen,
    for so many resources. Is there a way to access those articles online? E.g. via an electronic library?
    Thanks, Michael 

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    #87460

    Eileen
    Participant

    Michael,
    Go to the web site of American Statistical Assoc. You can at least order reprints or search their journals (?) for articles. You can’t read any of the articles online – as far as I know. For most technical articles, unless you are a paying member, you won’t be able to access online any articles.
    Good luck. Eileen-Quality Disciplines

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    #87461

    Michael Schlueter
    Participant

    Eileen,
    Thanks I will try it. Michael

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