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1.5 Shift – Six Sigma

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  • #68469

    vandehei
    Participant

    Probably not

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    #68474

    kbower50
    Participant

    The 2nd law of thermodynamics provides an incentive to give ourselves some margin of error when thinking of how a process will behave over time.  The use of 1.5sigma as a value throughout all industries is controversial.  If the reader is pragmatic, however, at least we’re moving away from the unrealistic viewpoint of a process fluctuating randomly around some fixed mean for the indefinite future.  SQC does it’s best to reach that state, but let’s be honest….. 
    Obviously, we should carry on, regardless!!  Of course capability indices, etc. require evidence of stability for parameter estimates to be used validly, so this concept shouldn’t be used as a scapegoat.  Incidentally, George Box has a nice discussion in Quality Engineering earlier this year.  Hope this helps.

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    #68477

    Boars
    Participant

     We will keep it simple…
    The 1.5 shift comes into play when you are talking about the type of data you are working with in terms of long term or short term.  Long-term data is when data has been collected from the process over many cycles.  In most transactional processes a cycle is most likely more than a year.  By collecting data over the long term your process will experience “shift and drift” (i.e.  high volumes, low volumes, under staffed, over staffed, and a variety of human and computer errors).  When you calculate your sigma score it will give you a long-term sigma.  If you would like to know how your process can perform over the sort term, sometimes called “entitlement”, add 1.5 to the sigma score.  Why 1.5 as oppose to 1.3256?  That discussion is for the statistical dissertation.
    Hope this helps,
    Boars

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    #68479

    vandehei
    Participant

    What BS

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    #27786

    Uma Maheswari Balasubramanian
    Member

    Could somebody please explain me the 1.5 shift that comes up in Six Sigma ?

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    #68509

    no name
    Participant

    You are right Ann! Thank you for your honesty.
    Simple explanation: “shift” happens everywhere!

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    #68513

    Ken Myers
    Participant

    Uma,
    Been there, and done that…  To get an idea about this concept please see the iSixSigma articles as follows:
    https://www.isixsigma.com/library/content/c010311a.asp
    https://www.isixsigma.com/library/content/c010701a.asp
    Have fun!
    Ken

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    #68524

    Dewayne
    Participant

    In spite of a couple of rather rude replies that were provided, I appreciate  your asking the question, Uma.  I have  had only a partial understanding of this point myself, and some of the information that has been supplied here helped with my further understanding of what is involved.
    I noticed that in the reference material that Ken has provided, there is a forum question of “Do you understand why a process mean may shift 1.5 sigma?” being provided, with 51.4% of the 778 replies stating they do not sufficiently understand the point, so it looks like we are  not alone in needing some assistance on this one.   
     
     
     

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    #68548

    melvin
    Participant

    “No Name”:
    While (in your opinion) “Ann” may be right or honest or straightforward or whatever you want to call it – this forum is really no place for the type of responses that she typically gives.  In fact, I opine that people like Ann (and there are others) take away credibility from this website.  Chat rooms are available (a dime a dozen) where people gather to verbally abuse one another and argue over meaningless matter.  This website forum, however, is for quality professionals to share insight on a hot topic – Six Sigma.
    Ann, if you want to comment – comment.  But, please have some data to back up such incredulous, cowardly comments such as “probably not” and “what BS”.
    “No name” – based on the above, find someone else to high five.
     

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