iSixSigma

Is There Anything Above 6 Sigma?

Six Sigma – iSixSigma Forums Old Forums General Is There Anything Above 6 Sigma?

Viewing 23 posts - 1 through 23 (of 23 total)
  • Author
    Posts
  • #44139

    S Venkat
    Member

    Hi,
    Can anybody give me instances (with proof) on any process working more than 6 Sigma? Like, 7 Sigma or 10 Sigma and so on….
    If so, how is the calculation done for it…
    Regards,S. Venkat

    1
    #141041

    Waskita
    Participant

    Venkat …
    You must be joking, right? Tell me you are ….
    I have never seen a process operates at 6 Sigma Level, not to mention 7 or even 10.
    6 sigma can be considered as a long term goal that we need to strive for i.e near perfection.
    The essence of the message by putting 6 sigma as the slogan is that for us to always continously improve.
    I’m more than happy to explain to you on the calculation  how we derive 3.4dppm for 6 sigma, also for 7 sigma, 10 sigma, 6.452 sigma, 5.001 sigma, etc. Just name it …
    Drop me an email if you’re interested to [email protected]
    But before you ask and send email, make sure you have a basic knowledge on normal distribution and how to read normal distribution table. Or else, it will be hard for you to imagine and understand what i mean
    Ciao
     
     

    0
    #141043

    Simon Wei
    Member

    This is a quite interesting topic.
    But I think from Total Process/Every Aspect point of view, above six sigma is Performance Excellence!
    Should you have any questions about that, I would very glad to discuss with you:-)
    Good day!
    Simon

    0
    #141049

    Hans
    Participant

    Take-off and landing of airplanes operate at a sigma level that is estimated at above 7 sigma. Mathematically you can set your denominator at 100 (Percent), 1,000,000 (DPMO) or any other number. So yes, there are a few “processes” that work at a level beyond six sigma.

    1
    #141052

    Waskita
    Participant

    You’re right Hans ….
    Sorry if i might be to pessimistic.
    But again, it really depends on our definition on a defect. If defect in airplane industry when talking about landing or take-off process is defined as no accident happen that can risk passanger’s lives, yes ..i agree it can be classified as more than six sigma performance. But if we can afford to drill down via survey, questionairre, etc what customer/passanger really expects during landing and take-off that it should be totally smooth, no significant vibration, etc …it may not be at six sigma performance level.
    Food for thought though ….In summary, yes you should be perfect or more than six sigma level when the risk involved is life. But ensure your operational definition is in line with the VOC
    regards,

    0
    #141058

    Hans
    Participant

    Ferry,
    I whole-heartedly agree: If dropping a thousand feet before landing counts as “no defect”, then I am glad I survived, but I am not quite sure if that meets customer’s expectations.
    My take on that whole “six sigma measure” is that it was a great sell at the beginning of the “movement” in the 1990s, but you make assumptions that may or may not hold, i.e. all customers have the same expectations, or at least that there are market segments that share expectations. Ironically, marketing is going beyond that model with new data mining technology allowing you to finetune services to an individual level. I don’t think that six sigma has embraced that concept yet.

    0
    #141060

    Andejrad Ich
    Participant

    On the subject of landing planes, and sigma measurement perspective:
    The airport (or system of all airports) see — say 1000 planes enter into their process every day and each is a defect opportunity (i.e., an opportunity for a crash).  So the airport system has 1000 defect opportunities every day and that system/process measures 7 sigma or better.
    But, for the air traffic controller(s), he has a — say — 25 step procedure to follow for each landing, and missing any of the 25 would be a defect (not that every one would lead to a crash necessarily, but missing a step is a defect).  So the air traffic controller(s) have 25000 defect opportunities each day. 
    Similarly, the pilot(s) in the plane have a 50 step procedure to execute (throwing switches, radio procedure, checking gages, etc.).  So the pilot(s) have 50000 defect opportunities each day. 
    So, let’s say, the air traffic controllers routinely skip step #12 on their procedure (they just can’t seem to remember that one) and the pilots tend to miss #7, #22, #27, and #34 on theirs (after all, it’s busy in there during landing).  So in this case, the air traffic controllers are operating at about 40,000 DPMO, which is 3.2 sigma.  The pilots are operating at about 80,000 DPMO, which is 2.9 sigma.  And yet the planes are landing successfully at better 7 sigma. 
    Just for the purpose of thinking/discussing, anyone have any thoughts, insights, comments on this scenario?  It’s not a quiz or riddle.  There are no right answers (because there isn’t a question).  Just….anyone have any thoughts to input?
    Andejrad Ich

    0
    #141061

    Andejrad Ich
    Participant

    And I think the point I might be trying to get at may be (…see, I don’t even know for sure):
    Can a processing line with 5 machines have each machine operating at 2 or 3 sigma, but what comes off the end of the 5 machine process measure as 7 sigma?
    And if so, isn’t it possible to mistakenly beat the hell out of the 5 machine operators for their machines’ 2 or 3 sigma performance when the process is actually the plant’s stellar 7 sigma performer?
    Andejrad Ich

    0
    #141062

    Haugen
    Participant

    You are compairing 7-sigma oranges to 3-sigma apples.  Different customers.  The 7-sigma at the end of the line, if you are comparing the line to your airplane example, is one set of final customer requirements.  The per-machine 3-sigma performance is – like the conrollers or pilots – internal measures that the customer does not see.  Internal customers, internal (in-process) sigma rates.

    0
    #141063

    Hans
    Participant

    JimH, agreed. The assumption behind the 7+ sigma calculation is that each plane has one opportunity of safely landing/taking off.

    0
    #141064

    Andejrad Ich
    Participant

    Right…but might such a situation be an indication that the operators are being burdened with unnecessary apples.  If the internal apples don’t contribute directly to delivery of oranges, then why demand/measure apples?  Why make operators hate their jobs trying to deliver apples when they have little or nothing to do with oranges and shouldn’t great care be taken to line these up?
    Andejrad Ich

    0
    #141066

    Andy S
    Participant

    To elaborate on Jim’s comments, these apples and oranges each have their own cost of quality. At the core of business strategy, the final customer requirements must be met and therefore a generalized 7 sigma level acceptance is great. No dealing with unhappy customers, losing them to competitors and the like. However, this is not enough! When internal processes operate at 3 sigma or the like we still have many associated costs. Rework, scrap, overtime, capacity, etc you guys know the drill. When it comes down to it, we are here to eliminate, or at least reduce, the cost of quality (or lack there of) in the entire SYSTEM!

    0
    #141069

    Andejrad Ich
    Participant

    So to tie this up then…
    A plane loaded with oranges leaves San Diego at 10:00 travelling north at 600 mph.  A second plane loaded with apples departs Seattle at 10:10 on the same day travelling south at 550 mph.  If the air traffic controller misses step #14 in a forest, does the Pope hear it?
    Andejrad Ich

    0
    #141071

    Belgus
    Participant

    Maybe one of his Bishops told him :-)

    0
    #141166

    lin
    Participant

    Any one of us could die any minute … heart attack, traffic accident, whatever.  I’ve had 30,485,666 such opportunities for death … which puts me well in excess of six sigma.
    It makes about as much sense as attaching a sigma level to any process. For some reality, read the articles here :
    http://users.bigpond.net.au/SixSigmaFallacies/

    0
    #141167

    Stevens
    Member

    Bill,
    I’m not so sure.  I have a cat that’s 13 years old.  It has already used up at least 2 of its nine lives. By my calculations that’s 2 defects per 6,832,000 opportunities … in other words a six sigma cat ! 
    Actually, I agree that sigma levels are nonsense.

    0
    #141168

    Craig
    Participant

    Bill,
    It’s easy to sit back and criticize, like the authors of the articles from your link. Dr Burns already got torn up due to a general ignorance of Six Sigma. I also saw an article written by a Motorola Quality Director, who I believe is only a newcomer to the company. (Came in with the GI acquisition). I can tell you as a former Motorolan that I am embarrassed by his writings and slanderings about Six Sigma. People who sit on their butts and write articles are certainly not directing quality in their organizations. It’s too bad that people don’t generally understand the six sigma is about variation reduction.
    What solutions to all these “wizards” suggest? I am sure we can rip apart anything they come up with, just like they do.

    0
    #141194

    lin
    Participant

    How was Dr Burns “torn up” as you suggest ?  What are the specific errors in his paper … it sounded very convincing to me.

    0
    #141195

    lin
    Participant

    From what I can see from previous posts there has been no critique of Dr Burns paper.  All I can find is childish personal attacks and gutter sniping.  Personal attacks are not appropriate with the large number of authors at the http://users.bigpond.net.au/SixSigmaFallacies/  site.  Let’s see some constructive discussion of the CONTENT of these papers.
    These papers do present clear and superior alternatives to six sigma. Dr Wheeler in particular spells this out clearly in his books.  Perhaps you feel that Dr Wheeler is flawed ?

    0
    #141196

    Abhi Phirke
    Participant

    Ferry, why don’t you just post the explaination on calculation of N dppm for M Sigma? Those like me, who are interested, can read and ask questions if necessaary. It will reduce step of emailing… improving the process to a slightly higher sigma. :)Anyway, if you wanna keep it to private circulation, its ok with me. In that case, can you please mail it to [email protected].

    0
    #141201

    Waskita
    Participant

    Hi Abhi …
    Thanks for your input. I’ve just sent via email as per your request on how to get ppm for different level of sigma.
    I have no bad intention at all by not sharing/posting the explanation in the forum since there are varieties of six sigma skill in this forum. Those who are already expert may find it too basic for them which may not be the case for the others.
    Besides, there are some illustration through pictures which can’t be accomodated through posting in this forum.
    So, drop me an email for the rest who’re interested. It’s just a 30 secs job for me to forward what i’ve sent to Venkat earlier …
     
    Cheers

    0
    #141211

    Craig
    Participant

    For starters, if there are problems with six sigma, it is because of those who think it is about “counting defects”. It is about reducing variation such that the probability of a defect is minimal.
    I would ask for my money back if a consultant said to simply change the spec limits. Where does it say this in the DMAIC methodology? Sure, widen them if the VOC supports this. I am a user of six sigma methodologies, and I increased my cpk to over 5 so we could TIGHTEN the spec limits and supply better material to the customer. Did I miss something in my training? It would have been alot easier to widen the spec limits. Sorry if I wasn’t paying attention in class.
    From Dr Burns article:
    The above shakes the very foundation of Six Sigma, but there’s a more fundamental problem. Six Sigma is a specification-driven methodology. Six Sigma is based on counting defects, and defects relate to the specification. It’s easy for consultants to claim they’ll halve defects. They simply change the specification. Specifications tell us nothing about what the process is doing. Specifications are the voice of the customer, not the process. If we’re to improve processes, we must listen to the process. The voice of the process is the control limit. Control limits have been and will always be based on three sigma.

    0
    #141213

    Waskita
    Participant

    Points noted and you’re 100% right hacl …
    Six sigma is not abut counting defects nor number crunching, but how to make a difference in reducing variation in the processes.
    However; nothing wrong either of being curious on some theoritical behind all the numbers as not all people may be aware of.
    Cheers,

    0
Viewing 23 posts - 1 through 23 (of 23 total)

The forum ‘General’ is closed to new topics and replies.