iSixSigma

Gabriel G贸mez

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  • #202368

    Gabriel G贸mez
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    you do not need P to perform the calculation, the approximation assumes that if the size of the sample is large enough, it will approach normal …

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    #202260

    Gabriel G贸mez
    Participant

    The Sigma level with DPMO is a approximation to normal distribution from binomial distribution; according with central limit theory, its due to the DPMO measure the number of trials and success (%) in each sample or success (%) in the Critical characteristic of the part. Remember that a part could have many opportunities to evaluate (CTQ’s).

    Example : Suppose that we have a process with this characteristic:
    Example:
    Units/shift = 30,000
    Defective parts = 300
    Defects observed = 350
    Opportunities = 15
    Dpu = 350/30,000 = .011
    DPMO = (.011/15) x 1,000,000 = 777
    Yield : 1-(0.011/15) = 99.9922%
    ZBench : 3.164 *From normal distribution tables
    Sigma Level: 4.664
    CPk Process: 1.55

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