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How many CTQs

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  • #45505

    Rakesh
    Participant

    Lets say we do a VOC and a baseline and find that there are 3 CTQs for the output of a particular process that needs to improve. Is it always best practice to target only one CTQ for a BB project? What happens if I include 2 of the CTQs in the same project?

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    #148891

    Monk
    Participant

    Rakesh,
    If you are asking the question from the six-sigma project perspective, you can have only one CTQ.
    There are situations, wherein CTQs are interlinked, you can mention just for reference and ensure that those are not deteriorated by the improvement in other CTQ. So track all the related CTQs, but focus on the one which you want to improve.
    Monk

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    #148898

    Haugen
    Participant

    ?What – only one CTQ?  Since when???
    I gotta go back and change a couple hundred projects – hope it’s not to late!  Thanks for the heads up!

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    #148899

    BritW
    Participant

    You may want to target only one CTQ, but you may have many.  The ideal is to perform yoru analysis and determine which one (or more) have the most effect on the outcome and focus on that.  However, do not ignore the other CTQ’s.  It is ok to work on more than one – especially if more than one affect your ability to meet your customer’s goal.

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    #148900

    Monk
    Participant

    The success and the failure of a six-sigma or any improvement project can be verified by a single metric, which is the CTQ for the project.
    Do you agree to the above statement ?
    Monk

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    #148903

    BritW
    Participant

    Not sure I agree totally Monk…from the definition of CTQ:
    Critical To Quality – CTQCTQs (Critical to Quality) are the key measurable characteristics of a product or process whose performance standards or specification limits must be met in order to satisfy the customer. They align improvement or design efforts with customer requirements.
    If my goal is to provide a cutomer their product and say two CTQ’s are color and size.  If I work on fixing only one CTQ, say color, and fix it, but can’t get the dimensions right, then the customer still considers the product a defect.  That particular project would require the team to work on two CTQ’s.

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    #148906

    Faz
    Participant

    If you have 1 or 10 CTQs, does the customer really care. All he/she wants is a GOOD part EVERYTIME. I thought the purpose of SS is to provide the customer with a GOOD part EVERYTIME, regardless of CTQs.

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    #148910

    Dale
    Participant

    I’ve had quite a few projects with more than one CTQ – but they need to be a logical grouping.  It sounds like that is the case for your project – several CTQs support a VOC.  You just need to be sure you understand the project will “fail” if 1 of 2 CTQs is not improved.  Most of the time, that statement will get them to change it to a primary, secondary metric.
    I think that is the key question:  is it valid the project failed (ie, the process really wasn’t improved) if only one CTQ was improved? 

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    #148973

    Rakesh
    Participant

    This is a good example. One approach says go and do one project and include both colour and size as CTQs to be targeted. Another approached says target Colour as CTQ, do a BB project, improve it and then focus on size and do another BB project to improve it. The issue is probably about focus. We have a discussion on focus(sequential phased improvement) vs speed of results (concurrent targeting). Which one is the better practice?

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    #148979

    Haugen
    Participant

    Rakesh,
    First, I applaud you for asking the right question – “which is the better practice”?  And the answer – of course – is “it depends”.  What is you capacity for scope?  What is the time/cost impact – better to do it at the same time, or put the other opportunities on a MGP?
    Part of the problem with the dogma of SS as taught in many courses is it leaves out the thinking process – that’s how you end up with people asserting that you can “only do one Primary Mertic!!”.  Guess what – you can do whatever makes sense in your project environment.  These are tools and methods to get the job done – not laws.

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    #148990

    BritW
    Participant

    Good response.

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    #148993

    DennisLadd
    Participant

    I tend to agree with your response.  The VOC of the customer dictates the direction and focus of improving a process.  In the earlier example, getting only the color right and not the size (or what ever the other CTQ was) addresses only half the problem.  I would certainly want to have a handle on both CTQ metrics to determine the change result and whether additional process enhancements are required, but overall, want to meet customer expectations.

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    #148999

    reg
    Participant

    There’s an excellent article in the September issue of ASQ’s Quality Progress magazine.  Follow this link: http://qic.asq.org/perl/search.pl?item=20707
    Basically, the article shows how to use the same sort of sophisticated metrics to identify CTQs from a market perspective as are used for the actual conduct of Six Sigma projects.  The article goes on to illustrate how to use the identification of performance gaps on CTQs (again, from a market perspective) to target key processes for the identification of Six Sigma projects.  The idea is that the use of CTQ performance gaps allows you to set Six Sigma priorities, and that you can drill down as far as your resources will allow.  More importantly, this market focused approach to the identification of CTQs will get your Six Sigma projects to be more strategically focused on market share and revenue enhancements, rather than just on cost reductions.  Check it out.

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    #149025

    Rakesh
    Participant

    Dear Reg
    I am not an ASQ member. Will be glad if you can share the resource. Maybe you can send the attachment at [email protected]
    Thanks!

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    #149047

    Jonathon Andell
    Participant

    Ideally we hope to find one CTQ that is highest priority. Sometimes that doesn’t work, so here are some other options:

    Determine whether one CTQ is dependent upon another; work to improve the one that controls
    During measure or analyze phase, investigate whether CTQ’s are correlated, andthus somewhat redundant
    The worst case is when the two CTQ’s are in direct conflict, like engine power and fuel economy. Then you need some advanced tools to establish specifications and find the best tradeoff position. But that’s another discussion.

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