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How to convert DPMO/Sigma to Cpk

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  • #32487

    Logan Luo
    Participant

    Does anyone know how to convert DPMO/Sigma to Cpk?
     
    Thanks

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    #86818

    SixSigma Sally
    Member

    Logan-
    Cpk = Z(short-term) which is sigma level  /  3
    However, if you are starting with DPMO, convert it to a decimal value(divide by 1,000,000), look this decimal value up in a standard normal curve(z table) and find the corresponding z. Minitab can do this as well. Anyway this is long term z. To convert to short term z which is sigma level:
    z(short term) which is sigma level = Z(long term) + 1.5
    then you can plug into the equation above to get Cpk
    Hope this helps.

    0
    #86837

    Logan Luo
    Participant

    That is exactly the answer I was looking for. Now I can close the loop of my calculator. 
    In stead of looking Z value in a table, I designed this gadget which is similar to the one in this website to calculate the DPMO, Z value, Yield tp and Cpk for me .

    Thanks
     

    0
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