iSixSigma

Donald Wheeler says shift is bigger than 1.5 sigma

Six Sigma – iSixSigma Forums Old Forums General Donald Wheeler says shift is bigger than 1.5 sigma

Viewing 16 posts - 1 through 16 (of 16 total)
  • Author
    Posts
  • #45283

    Spoon
    Member

    I did some more investigation and found the following from Donald Wheeler about the shift factor: 
    “Techniques for analyzing small amounts of data will tend to be slow to detect shifts in the process average that amount to less than 1.5 standard deviations.  … Shifts of 3.0, 4.5, and 6.0 standard deviations were used in Figure 8 simply because shifts of this size are quite common in virtually all production processes. Moreover, as will be illustrated in the next section, even larger shifts are not uncommon. Thus, the consequences shown in Figure 8 do not exaggerate or overstate the situation in the least …Thus the third problem with the six-sigma parts-per-million values is their dependence upon the assumption that a 1.5 standard deviation shift in location is a worst-case scenario. Not only is this incorrect, it is actually the opposite of the truth.  In the previous section we saw that a 1.5 standard deviation shift was actually a best case number.”
     
    Reference: The Six Sigma Zone, Donald Wheeler
     
    Stan and a several other frequent posters have argued many times on this forum that the “shift factor” is actually less than 1.5 but the guru of SPC says different.  This just shows how the self proclaimed experts on this site really do not know what they are talking about.  Just more “opinions” rather than facts.
     

    0
    #147525

    BB
    Participant

    Reigle,
    This is clearly fraud. 
    Where is that lawyer ?
    You have obviously read Wheeler and you understand the point he is making.  Wheeler makes the point that process averages may shift by any amount. Shifts are not in any way “limited” to 1.5.  Points out of control can fall anywhere.
    You have also suggested that the 1.5 is a “correction”, not a “shift”. Make up your mind.  Conning people can be tricky can’t it ?

    0
    #147526

    Bash Me Too
    Participant

    BB:
    Just read the quote from Wheeler and weep!  You’ve been had buddy.  Everyone can read the article quote for themselves and see how you (under different names) have been talking out the wrong end.   Just go away and lick your wounds, retire for the night and your public embarrasement will just be a bad dream tomorrow (until you again read the quotes from Dr. Wheeler).

    0
    #147533

    mand
    Member

    Reigle,
    What on earth are you talking about ? 
    Wheeler says there is no limit to the magnitude of special causes or process shifts. They may be 4, 5, 6 sigma, anything !  There is no magical 1.5 limit as you claim.
     

    0
    #147543

    Bash Me Too
    Participant

    Sam:
    Read Spoons quote again.  Wheeler says “Thus the third problem with the six-sigma parts-per-million values is their dependence upon the assumption that a 1.5 standard deviation shift in location is a worst-case scenario. Not only is this incorrect, it is actually the opposite of the truth.  In the previous section we saw that a 1.5 standard deviation shift was actually a best case number.”
    Harry says its is worst case and Wheeler says its is best case, but a few of the self professed experts on this site (like Stan) say there is no shift at all.  Stan says any process under SPC control will have ZERO shift.
    It don’t take a rocket scientist to figure out that Stan is flat wrong.  Processes that are under SPC control do experience shift and drift over time.  The only real question is by how much?  Is it 1.5 best case or worst case.  Who cares!  The point is to make your processes insensitive to shift and drift, don’t rely just on SPC.  Simply knowing they will move around is a better assumption than believing they will not move around at all.

    0
    #147544

    mand
    Member

    Reigle,
    Fraud has become second nature to you hasn’t it ?
    Wheeler’s quote that you have given is a discussion of unpredictable processes, page 9:
    http://www.spcpress.com/ink_pdfs/The%20Final%206%20Sigma%20Zone.pdf
    Wheeler points out that the six sigma model assumes unpredictable processes don’t shift by more than 1.5 sigma. He shows how this is total nonsense.
    Readers here should read Wheeler’s article and make up their own minds.

    0
    #147547

    QED
    Participant

    Reigle Stewart proposed using a ng = 30 to study shifts on SPC charts. The maximum shift on a n=3, g =10 chart is about 0.6 micron.
    Who cares anyway, because any decent process engineer would set up the process in a insensitive part of the process! Is it any wonder Japanese quality still leads the world.
    This whole theory of shifts could only contrived by someone who has little or no experience of actual process improvement! Someone who has spent their entire career sitting in little back offices arguing with themselves and others instead of going to gemba and solving some problems.

    0
    #147569

    ABC
    Participant

    Someone who has spent their entire career sitting in little back offices arguing with themselves and others instead of going to gemba and solving some problems … that sums up the life of “Bash Me Too”, aka “Spoon” aka their various nemeses … It looks like “Bash Me Too” has been outed :-)))))))))))))))))))))))

    0
    #147572

    Spoon
    Member

    abc.
    OK.  You’ve beat me up. I’m out.  Wow, you are really intimidating. Oooohh, I don’t want to post anymore since someone said I’m out of here. 
    There now, did that make your wedgie feel good?  Grab of cup of coffee, jump on and enjoy the ride today.

    0
    #147575

    Mikel
    Member

    Basher Boy Reigle,
    You said –  Harry says its is worst case and Wheeler says its is best case, but a few of the self professed experts on this site (like Stan) say there is no shift at all.  Stan says any process under SPC control will have ZERO shift.
    It don’t take a rocket scientist to figure out that Stan is flat wrong.
    It may not take a rocket scientist, but the real question is does this fat old Mechanical Engineer have a reading comprehension problem or are you just a liar?
    Go find one post out of the thousands out there from me where I claim zero shift. Let me help you – you will not find one. What I do say is the assumption of 1.5 is okay in the absence of real data. I also say much better control is possible with just a little process knowledge and some of the Lean tool set. Use SPC if and only if you cannot find a better control method.
    Are you a liar just trying to divert attention or can you just not understand what you read?

    0
    #147579

    Bash Me Too
    Participant

    Stan:
    Here is one of your quotes that you say doesn’t exist:
     
    “There are lots of good things about six sigma but the 1.5 shift nonsense is not on of them.”
     
    Posted by: Stan
    Posted on: Thursday, 4th November 2004, 3:35 AM
     
    Be more factual in the future and people might take you more seriously.  Also, you have posted so many “opinions” its no wonder you don’t remember what you say.
     

    0
    #147580

    Mikel
    Member

    Did you get low scores in reading comprehension in elementary school?
    Saying the 1.5 is nonsense and saying zero shift are two completely dfferent things.
    Are you not smart enough to know that?

    0
    #147581

    Bash Me Too
    Participant

    Stan:
    OK, whatever you say, but at the end of the day, everyone can see by the quote from your recent post that your current babble is nothing more than a thin vail of justification to back peddle.  You really need to remember what you have said in the past!  Would you like to see some more of your quotes on this subject?  You got some real duzzies out there!  Especially those quotes where you contradict your self and the likes of Dr. Wheeler.
    Nonetheless, its really good to see you finally fess up to the practical utility of the 1.5 sigma shift in the absense of data.  This is exactly what Dr. Harry has said in his publications (only use the shift if you don’t have data)  Do you need some quotes on this too?
    My recomendation to you would be to lay low for awhile and other posters will soon forget your nonsense.

    0
    #147590

    Mikel
    Member

    Basher honey,
    Please share some of those duzzies (I believe the word you were looking for is doozy or doozies).
    Show me where I contradict myself.
    I have no doubt about contradicting Wheeler – he is a smart guy but doesn’t know enough about MSA to give advice beyond experiements and he relies too heavily on SPC.
    I have always said that the 1.5 was useful but to go get data. The building of the shift permanently into the sigma tables is just plain stupidity. The “proofs” and the Bender and all the other stuff is just hand waving and I have also always said that.
    With that said, please entertain us with some duzzies.

    0
    #147597

    Ed
    Participant

    Reigle,
    What sort of idiot are you ?
    With no data, you know nothing about a process.
    If no one has seen her, why assume she’s ugly ?  Don’t you think so girls ?

    0
    #147917

    Lebowski
    Participant

    One week off for Thanksgiving and this has really deteriorated. We were on record pace for length of a string according to Darth and we get shut down.
    Reigle,Bash Me Too, Spoon or whatever took the same tactic with me as well. The quote Basher Boy uses is a fine example of his complete lack of understanding of the English language. They misquote and when you call them on it they screasm you are back peddling rather than admit after all their blather about accuracy they have absolutely no idea of either accurracy or precision.
    Lebowski

    0
Viewing 16 posts - 1 through 16 (of 16 total)

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