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How do I define opputunities?

Six Sigma – iSixSigma Forums Old Forums General How do I define opputunities?

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  • #28317

    Helen
    Participant

    Can anyone help me to define oppurtunities for defects, please? An example of one of the processes I work with has 8 worksteps, uses 17 components, typically has a start qty of 100 and on average 3 defects are found in the process.
    I am ‘presuming’ that oppurtunites = 8+17+100 = 125
    Am I correct?

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    #70340

    James A
    Participant

    Morning(?) Helen,
    It depends if you are looking at the macro or micro level at your process. At the macro level, with 8 processes, I would view the Opportunities for Defects to be 8 – as the product either comes out ‘good’ or ‘bad’ after each process.  At the micro level, looking at each of the 17 components, and its position/insertion/function/whatever there are another 17 opportunities – but within each of those opportunities, there may be further detail needed to define the problem more accurately. 
    In other words, keep peeling away the layers of the onion until either your eyes water uncontrollably, or you get the data you need to fix the problem (the Y=f(x) bit, but each f(x) has its own f(x)s as well)
    Batch quantity and the number of incorrect parts should only give you an indication of the likelihood of success 3/100=0.03 so success will be (1-0.03) = 0.97 or 97%.  With defects per unit now established as 0.03, multiplying that by 1,000,000 gives a value of 30,000
    DPMO (Defects per million opportunities) = 30,000/No. of opportunities for error, which is now a process complexity biased value.
    Does this help?
    regards
    James

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    #70343

    Jaran S.
    Participant

    I think your oppurtunities should be at least :
    8*17*100  
    Jaran S.

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    #70344

    James A
    Participant

    Helen and Jaran,
    Better still, click on the “Sigma Calculator” on this page, and below it you will see a link to “Learn how to define units and opportunities”.
    This will also provide more detail.
    regards
    James

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    #70346

    Helen
    Participant

    Thanks for responding James & Jaran… I have searched the web for info on this and the best I can come up with is…
    Simply stated, opportunities are the total number of chances per unit to have a defect. Each opportunity must be independent of other opportunities and, like a unit, must be measurable and observable. The final requirement of an opportunity is that it directly relates to the customer CTQ (see Start With The Customer above). The total count of opportunities indicates the complexity of a product or service.
    Am I missing something? If an opportunity is as defined above then surely you must also include; the # of operators, the # of worksteps, environmental conditions, process capability, components etc etc etc… at what point do you draw the line? I am only begining to measure DPMO, so as a starting point would it be accurate to just include my number of worksteps as my opportunity for defects? Also using the 100*8*17 in the calculator tells me my process sigma is infinite with 0 PPM, which is far from reality …. I’m still confused here …. your help would be majorly appreciated….
    Rgds,
    Helen
     

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    #70350

    Marc Richardson
    Participant

    Helen,Here is my take:I make apart. My inspection sheet, developed based on the FMEA I conducted where I identified the potential failures for the product, has 10 characteristics. Every time I inspect the product, I inspect it for these 10 charateristics. Let’s say that 7 of the charatcteristics are continuous (can be measured) and 3 are discrete (a go/no go decision must be made). Further, let’s say that I produced 10,000 parts per work order. That would mean that there are 100,000 opportunities for error for each work order.
    This is a pragmetic cut-off point. One could argue that all the characteristics on the drawing are opportunities for error.Marc Richardson
    Sr. Quality Assurance Engineer

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    #70351

    Jaran S.
    Participant

    Thank a lot.
    Jaran S.

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    #70354

    Helen
    Participant

    Thanks Marc – that’s exactly what I wanted to know.

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    #70356

    James A
    Participant

    Marc,
    Thanks for the posting – and including the use of FMEA.
    My only query is on the inclusion of batch size in the ‘opportunities’ calculation.  Surely, the ‘opportunities’ refer to the unit being produced, not the batch size, and relate to what the customer will find dissatisfying.
    ie if I were to buy a PC, and one of its ports didn’t work, that would (or should) represent a missed opportunity.  As a customer, I wouldn’t be impressed at being told that the other 400,000 in the batch were OK.
    Have I missed something here?  Thanks.
    regards
    James

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    #70365

    Marc Richardson
    Participant

    I don’t think you’ve missed a thing.
    The trick is to identify all the things that could possibly go wrong with a unit. There are many ways of doing this and in my experience, none of them is 100% effective. Ussually, people agree on some practical standard of what is most likely to go wrong.
    It is a commonly accepted practice to multiply the number of things that can go wrong with a single unit or transaction by the number of units or transactions being produced or executed to arrive at the number of opportunities. This can and does create large numbers of ‘opportunities’ against which a small number of defects can look impressive.
    This is the basis of the charge that 6s practioners inflate the number of opportunities in order to show a 3.4 DPMO. Personaly, I prefer to stick with the familiar PPM measure. Low DPMO values are meaningless to customers who continue to receive product that does not meet or exceed their expectations.Marc Richardson
    Sr. Quality Assurance Eng.

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    #70405

    Mikel
    Member

    Opportunities are not the things you inspect.Consider two groups running the same process making the same product. One group does not know their process well and has to depend on inspection/test to protect their customer. They inspect or test 50 different things. The other group truely understands their process and does not need inspections and test. They protect their customer through controls and poke yoke.The group that does not know their process has more opportunity by your definition. This makes no sense and isn’t even close to being right. Both groups have the same number of opportunities.

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    #70407

    Mikel
    Member

    Marc,I would suggest this last post reflects your misunderstanding of opportunities.

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    #70409

    Patrick
    Participant

    Stan,
    If you feel that Mark doesn’t understand how to define opportunities, why don’t you provide your understanding rather than just stating that he doesn’t understand it. What benefit does that have to anyone on this forum besides tearing down contributions? Please, let’s all work to be a little more constructive in our feedback. Isn’t this what we expect when we work with our businesses?
    Sincerely,Patrick

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    #70412

    Marc Richardson
    Participant

    Stan,I still don’t understand how you are defining opportunities. Please provide us with your formula for calculating DPMO and I’m sure that will clear things up. I’m always willing to learn.Thanks,
    Marc Richardson
    Sr. Quality Assurance Engineer

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    #70422

    Edwards
    Participant

    My understanding is that opps for error helps to compare the performance of  processes of differing levels of process complexity. It is a process feature and does not relate to a particular batch size.
    For example, for a two stage process that produces machined parts. If at the inspection point at the end of the first stage there are seven items on the inspection check sheet then that process has seven opps for error. If the second stage has four checksheet items then the opps for error of the total process is eleven.
    When we calculate the dpmo for the process, we can use the formula:
    dpmo = observed defects/unit x (1/total opps for error) x 1,000,000
    In other words the defects per batch is covered in the defects/unit computation
    This seems to be a conservative approach
    Hope it helps

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    #70423

    Dewi Lloyd
    Participant

    Hi Helen,
    Sigma rating  =     No of defects  x  1,000,000
                            No of Units x  No of opportunites
    For instance, if we consider the quality of an item of clothing sold at retailers, and out of 650 items sold, 2 fail for a broken zip and one for its’ general condition, then.
    DPMO =    (2+1) x 1,000,000     =   1538
                              3 x 650
    One other point… some texts would quote 769 as the answer here and not 1538.  This is because some scenarios exist where scores below the LCL are OK e.g. time taken for a letter to reach its’ destination – if it is less than the average, then this is good news!
    Hope this helps.  Email me at [email protected] if I can help any further – I am not an expert, but I will try.
    Regards
     
    Dewi
     
     

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    #70435

    Mikel
    Member

    Marc,Opportunities are simple. They are the things that must go right, not the number of things that can go wrong (creative minds can make this number approach infinity) or the number of things we test or inspect for (again creative minds can dream of non relevant tests and inspections instead of solving problems, not only is this non-value added, it disrupts flow of products and services).To count opportunities, use your process map, not your control plan. Identify value added activities to the detail level of what the process does to transform the product or service. This is the things, which are of value to your customer, which must go right. This is your real opportunitity. This way the good process managers get the sme number of opportunities as the poor process manager — a level playing field can be had and we know where to go learn.

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    #70436

    Mikel
    Member

    Patrick,Point taken — see my post to Marc.

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    #77839

    Lee Brown
    Participant

    The customer’s satisfaction is the ultimate measure of our success. The Six Sigma approach to customer satisfaction takes that idea literally. That is why before you can begin calculating your DPMO, you must first identify your customers expectations of your product/service. For example; If your product has 4 drawers, 2 key locks, and is painted. Your customer would most likely be interested in the following attributes:

    delivered on-time (1 opportunity)
    cosmetic appeal – correct color/texture (1 opportunity)
    each drawer functions correctly (4 opportunities)
    both key locks function correctly (2 opportunities)
    No damage to the product (1 opportunity)
    This means your product, although it may include 100 components, and have 40 characteristics identified in a FMEA and inspected for, actually has 9 opportunities to fail from the customers point of view.
    I hope this helps.
    -Lee

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    #77841

    Ron
    Member

    Opportunities are what you decide they are. If you are in a manufacturing world they are the dimensions on a part if you are in a service industry they may be customer KQC’s. But whatever industry you are in you must decide what they are and baseline it. Remeber the metric drives the action so if you have many many opportunites you will probably inflate your sigma values.
    At Allied Signal it was decided that opportunities by definition was three times the bill of material. This precluded gamesmenship when it came to calculating sigma values.
    In your scenario you would examine what operations were performed at each step of the process and what specification were affected. You would then calculate a first pass yield at each step, calculate your RTY and select your sigma value based in yield.
     

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    #93791

    TaurusFerny
    Member

    Problem :
    Units Produced = P = 100
    Defects Found = D = 3
    Parts per Unit = PPU = 17
    Number of Operations = Op = 8
    Solution:
    Defects per Unit = DPU = 3/100 = 0.03
    Defects per Opportunity = DPO = DPU/PPU  = 0.03/17 = 0.001764
    Defects per Million Opportunities = DPMO = 1764
    Throughput Yield = Ytp =  e (-0.03) = 0.97
    Normalized Yield per Operation = (Ytp) ^(1/Op)
                                                      = (0.97)^(1/8)
                                                      = 0.996
    OP PPU P   Therefore your equation  8+17+100 is wrong.
    Regards

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    #131791

    Tao
    Member

    Hi Helen,
    In your case you need to compute the output at each of 8 steps & get the sigmas at each step. Output of step 1 will be Input of step2.
    Also according to me there are is only 1 opportunity for a qty to work. Either it is defective or it is not.
    So as per me there can be only 1 opportunity for defect.
    Most welcome for discussions,
    Sophia

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    #151387

    Dave Barr
    Participant

    I have a definition of:-

    An Opportunity is a measured output from a Customer Required (CTQ), Value Added process or process step.
    and would appreciate feedback.
    Dave

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    #151394

    Mikel
    Member

    The measured part of the definition is nonsense.
    One of the real financial benefits of achieving a high capability (choose your own definition here, but mine is Cp>1.67, Cpk>1.5, and Cpm>1.33) is the tremendous reduction or elimination of the non value added activities called test and inspection.
    Using the measured definition, opportunities would decrease as capability increases which makes no sense at all.
    This definition comes from the active vs passive arguement put forth in The Vision of Six Sigma by Harry oublished in 1994 (lovingly referred to as the white catoon book). Just know that the person making this arguement thinks that the DMAIC method is superior to Lean for reducing time and inventory.

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    #158450

    Mustafa Anis
    Participant

    hi Helen
    To calculate opportunities do this…..
    18*17*100 = 30600
    ok tk care
    i,m doing Masters in Quality Mgmt.
    bye

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    #158461

    Mikel
    Member

    I hope your masters work is more rigorous than your ability to calculate opportunitities.
    From the information given opportunities are at most (8+17)*100

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    #162759

    Andhale
    Participant

    Any component of the process or any characteristic of the product is an opportunity. This is an opportunity because it may give rise to a defect in the process or the product.

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    #187013

    Peter Schillings
    Participant

    Hi,
    DPMO equals (number of defect divided by number of units)x1000000 and this divided by the opportunities per unit.
    So in your case:
    DPMO = ((3/100)x1000000)/ 17 = 1764

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