4 sigma
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Mikel.
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January 27, 2005 at 8:08 pm #38214
Waldemar MartinezMember@Waldemar-MartinezInclude @Waldemar-Martinez in your post and this person will
be notified via email.A company operating at four sigma would spend approximately what percentage of sales as cost of poor quality?
a. 15
b. 3.4
c. 0.34
d. 8.5
e. 20
Can you tell me how to come out with the answer. explaine please.0January 27, 2005 at 8:48 pm #114109According to a Black Belt class sponsored by ASQ I attended a little over 2 years ago, there was a slide that showed 4 sigma to be approximately equal to a cost of poor quality of 15-20% of sales. The source listed for that was Journal for Quality and Participation, Strategy and Planning Analysis. How specifically it was calculated, I don’t know. The table listed estimates for COPQ for sigma values from 1-6.
0January 27, 2005 at 8:50 pm #114110The 4 sigma is 99.3790% or 6,210 D/M or 0.621 D/H
.621/4 sigma = .155*100= 15.525 or 15%
0January 27, 2005 at 10:36 pm #114118Karlos,
Interesting. Why the .621/4 ?0January 28, 2005 at 2:14 am #114126My friend, you might have to review the chapter on process capabilities.
Let me give you a hint.
The process capability is nothing but the ratio of the specified spread to the process spread, in this case:But for this case, we are interested in the tails of the curve outside the specified limits (process incapability, if you wish). And we have already determined that that spread is equal to 0.621, so all we need to do is divide it by the process spread which is .
I hope that this will help.Issa0January 28, 2005 at 2:17 am #114127Mr. Martinez, I am your teacher and happened to notice you posting one of your test questions on this site. You are busted!! The idea is for you to do your own work. I will be deducting points from this exam as a result of your actions.
0January 28, 2005 at 2:25 am #114128Let me get the mess off the way first.
My friend, you might have to review the chapter on process capabilities.
Let me give you a hint.
The process capability Cp is nothing but the ratio of the specified spread to the process spread, in this case:
Cp = (USL LSL)/ 4 sigma
But for this case, we are interested in the tails of the curve outside the specified limits (process incapability, if you wish). And we have already determined that that spread is equal to 0.621, so all we need to do is divide it by the process spread which is 4 sigma.
I hope that this will help.
Issa
0January 28, 2005 at 2:56 pm #114149Does this mean we need to add an ethics section to the GB / BB exams?
0January 28, 2005 at 5:58 pm #114158Teacher:
Looks like you found a ‘failure mode’Good detective work0January 28, 2005 at 6:25 pm #114161Sigma Level | D/M Cost of Quality
20January 28, 2005 at 6:25 pm #114162Sigma Level | D/M Cost of Quality
20January 28, 2005 at 6:28 pm #114163Sigma level D/M Cost of Quality
2 308, 537 not applicable
3 66,807 25 – 40% of sales
4 6,210 15 – 25% of sales
5 233 5- 15% of sales0January 31, 2005 at 2:31 pm #114223Hi Wally,
Nice summary…. Would you mind citing your source(s)?
Best Regards,
Bob J0January 31, 2005 at 2:42 pm #114224Wally,
Never mind….
Mike cited a good reference in another related thread…. https://www.isixsigma.com/forum/showmessage.asp?messageID=63228
thanks anyway….
Best Regards,
Bob J0January 31, 2005 at 3:06 pm #114228It came from the Breakthrough management strategy by Mikel Harry and Richard Schroeder
0January 31, 2005 at 3:07 pm #114229Wally,
Thanks! Much appreciated!
Best Regards,
Bob J0January 31, 2005 at 3:10 pm #114231So the real question is what was their source? One of the two of them is known for not having data.
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