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4 sigma

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Viewing 17 posts - 1 through 17 (of 17 total)
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  • January 27, 2005 at 8:08 pm #38214

    Waldemar Martinez
    ★ 10 Years ★
    Member

    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.

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    January 27, 2005 at 8:48 pm #114109

    Dennis
    ★ 10 Years ★
    Participant

    According 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.

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    January 27, 2005 at 8:50 pm #114110

    Karlos
    ★ 10 Years ★
    Participant

    The 4 sigma is 99.3790% or 6,210 D/M or  0.621 D/H
    .621/4 sigma = .155*100= 15.525 or 15%
     

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    January 27, 2005 at 10:36 pm #114118

    e
    ★ 10 Years ★
    Participant

    Karlos,
    Interesting.  Why the .621/4                ?

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    January 28, 2005 at 2:14 am #114126

    Issa
    ★ 10 Years ★
    Participant

    My 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.Issa  

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    January 28, 2005 at 2:17 am #114127

    Teacher
    ★ 10 Years ★
    Member

    Mr. 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.

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    January 28, 2005 at 2:25 am #114128

    Issa
    ★ 10 Years ★
    Participant

    Let 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 
     

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    January 28, 2005 at 2:56 pm #114149

    Dale
    ★ 10 Years ★
    Participant

    Does this mean we need to add an ethics section to the GB / BB exams?

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    January 28, 2005 at 5:58 pm #114158

    fmea
    ★ 10 Years ★
    Participant

    Teacher:
    Looks like you found a ‘failure mode’Good detective work

    0
    January 28, 2005 at 6:25 pm #114161

    Wally
    ★ 10 Years ★
    Member

    Sigma Level | D/M Cost of Quality
    2 

    0
    January 28, 2005 at 6:25 pm #114162

    Wally
    ★ 10 Years ★
    Member

    Sigma Level | D/M Cost of Quality
    2

    0
    January 28, 2005 at 6:28 pm #114163

    Wally
    ★ 10 Years ★
    Member

    Sigma 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 sales

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    January 31, 2005 at 2:31 pm #114223

    Bob J
    ★ 10 Years ★
    Participant

    Hi Wally,
    Nice summary….  Would you mind citing your source(s)?
    Best Regards,
    Bob J

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    January 31, 2005 at 2:42 pm #114224

    Bob J
    ★ 10 Years ★
    Participant

    Wally,
    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 J

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    January 31, 2005 at 3:06 pm #114228

    Wally
    ★ 10 Years ★
    Member

    It came from the Breakthrough management strategy by Mikel Harry and Richard Schroeder

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    January 31, 2005 at 3:07 pm #114229

    Bob J
    ★ 10 Years ★
    Participant

    Wally,
    Thanks!  Much appreciated!
    Best Regards,
    Bob J

    0
    January 31, 2005 at 3:10 pm #114231

    Mikel
    ★ 10 Years ★
    Member

    So the real question is what was their source? One of the two of them is known for not having data.
     

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