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how to understand it?

Six Sigma – iSixSigma Forums Old Forums General how to understand it?

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  • #42093

    Joanna
    Participant

    Enter your process opportunities and defects and press the “Calculate” button.

    Switch To: Advanced Mode

    Opportunities

    Defects

    Calculation Results

    DPMO

    Defects (%)

    Yield (%)

    Process Sigma

    © iSixSigma 2000-2006

     
    What does it mean? I have 1000000 opportunities, so e.g on 10000 invoices I have the possibility to make 1000000 mistakes. I have 3,4 mistakes in reality, so why my sigma is not 6, but 5,4? Do I understand sth wrongly? Thank you for reply

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    #132694

    Jered Horn
    Participant

    Not sure that I understand…”so e.g on 10000 invoices I have the possibility to make 1000000 mistakes”.
    If you key in “3.4” instead of “3,4”, the calculator will interpret 3.4 defects per million opportunities instead of 34.  That will give you the desired “6” Process Sigma result.

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    #132702

    joan
    Participant

     

    Enter your process opportunities and defects and press the “Calculate” button.

    Switch To: Advanced Mode

    Opportunities

    Defects

    Calculation Results

    DPMO

    Defects (%)

    Yield (%)

    Process Sigma

    © iSixSigma 2000-2006

    Thank you. Now, what does it mean, that DPMO=3 and yield=100?

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    #132705

    Jered Horn
    Participant

    It’s not really very useful information…
    DPMO = 3…That means you can expect 3 defects per million opportunities.  The calculator rounded 3.4 to 3.
    Yield % = 100…That means you can expect 100 good parts out of 100.  The calculator rounded 99.9997 to 100.

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    #132713

    TipperG
    Member

    Hmmm,
    Let’s take one step back. The numbers you fill in in the fields opportunities and defects is what YOU have measured in YOUR process. When you press on calculate you then get the DPMO, Defect Rate, Yield & Sigma level of your process.
    So let us see what the different input terms (opportunity, defect) mean in your context.
    From your message I assume we are looking at an invoicing process (seeing you talk about producing invoices).
    Now, the most singular output of the process is 1 invoice, so the Product = 1 invoice
    On each invoice there are several fields containing information. A field containing incorrect information is called a Defect. (An invoice containing one or more incorrect fields is called Defective.)
    The opportunities for a defect is simply the number of fields that can be either correct or incorrect. For the sake of the example let’s assume an invoice contains 10 such fields.
    Now let us imagine that over the past month, 10,000 invoices have been produced.
    As each invoice has 10 opportunities for mistake, the total number of opportunities is 10 * 10,000 = 100,000
    You looked at each invoice and found in total 5,673 fields were incorrect => so there are 5,673 defects
    Plug these numbers in the calculator and you get
    DPMO = number of defects to be expected if a million invoices are made = ( DEFECTS / TOTAL OPPORTUNITIES ) * 1,000,000 = ( 5,673 / 100,000 ) * 1,000,000 = 56,730
    Defect Rate (%) = DEFECTS / TOTAL OPPORTUNITIES  = 5,673 / 100,000 = 0.05673 or 5.673 %
    Yield (%) = 1 – Defect Rate = 1 – 0.05673 = 0.94327 or 94.327 %
    Process Sigma = z-score corresponding with DPMO found above = 3.08
    Hope this clarifies

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    #132715

    Jered Horn
    Participant

    tipperg,
    That is an excellent clarification.
    Is this right, though?…
    “DPMO = number of defects to be expected if a million invoices are made…”
    Shouldn’t it be…”DPMO = number of defects to be expected per million opportunities…”?
    Just want to make sure.

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    #132716

    TipperG
    Member

    hi HornJM,
    yup, your phrasing is the correct one, I forgot about the 10 opps per invoice when I wrote my sentence.
    thanks for pointing that out
     

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