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3 sigma better than 6

Six Sigma – iSixSigma Forums Old Forums General 3 sigma better than 6

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  • #44714

    Sinnicks
    Participant

    A simulation. Normal distribution. 1000 points. Mean = 100, SD=1
    Six sigma plot shows mean floating by +/-1.5 sigma

     

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    #143869

    WYMI
    Member

    The subject line of your post caught my attention, but there was nothing in the body of the post except for some links that have warnings associated with them.  Am I missing something?

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    #143881

    Brit
    Participant

    Did you have something for the forum?

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    #143883

    Simon W
    Member

    Mark,
    It only indicates the precision and accurancy not indicates 3 sigma is better than 6 sigma.
    Hope be helpful.
    Simon

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    #143991

    Sinnicks
    Participant

    The graphs show a stable 3 sigma process compared to a six sigma process with a +/-1.5 sigma floating mean.
    http://users.bigpond.net.au/SixSigmaFallacies/images/15cc.jpg
    The six sigma process is seen to be wildly out of control !!!

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    #143999

    Simon W
    Member

    Dear Mark,
    I mean there must be some assignable causes resulted in this periodic flow.
    What are they and how can you improve them, I think, should be your focos at this stage.
    Not means that 3 sigma is better than six sigma.
    Hope be clearer.
    Good luck,
    Simon

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    #144047

    Sinnicks
    Participant

    Exactly !!!
    Why didn’t Bill Smith at Motorola realise this ?
    The +/-1.5 sigma drift and 3.4 DPMO is nonsense !!!!

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    #144056

    Orang_Utan
    Participant

    The graph clearly show that there are special causes in that simulated six sigma process.You shall compare 3-sigma common causes against 6-sigma common causes, not against 6-sigma common and special causes. Apple vs orange is not an appropriate comparison.

    The term used by Bill Smith is shift in the mean, not drift in the mean.

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