# Which one is right

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• #39940 Ruddy
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I am confuse the how to calculate the sgima level of process, please tell me below which one is right and which is wrong clearly.We have 1,000,000 productions, find defect is 8,000. defect opportunity is 1.Then case 1DPMO is 8,000 according to the ASQ six sigmal primer appendix, the sigmal level is 2.9 sigma(with 1.5 shift)case2DPU is 0.008 DPMO=0.008Y= RTY= e-DPU=0.992Probablity of defect is P(d)=1-Y = 1-0.992=0.008then use Z value table is 2.41and add 1.5 shift, then the sigma level is 2.41+1.5=3.9 sigmalCase3.using formula sigmal level= 0.8406+ SQRT(29.37-(2.221*ln(PPM)))then 0.846+SQRT(29.37-(2.221*ln8000))=3.9 sigmalquestion 1:the resuult of case 2 and 3 are different with case1 which one is right?question2:if we want to know the cpk of this process, is 8,000/1,000,000=0.8% just P value(because it is attribute data), that is right?thanks Michael

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