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what is the difference between run control chart

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  • #49987

    Hardik
    Participant

    Hi ,
    i am pretty new to stats world can anyone help me in understanding run chart & control chart , or what is the difference between them

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    #171686

    Outlier, MDSB
    Participant

    hardik,
    That’s a reasonable basic question if you are new to statistics and the concepts of statistical process control. The basic difference is that a run chart simply plots data in the order it was collected to show data over time. A control chart does more. It shows you not just the performance over time but shows the process mean and calculates upper and lower “control limits.” The basic purpose of a control chart is to show you whether your process is stable and to alert you to to any “special cause” variation that needs investigating.
    That is a REALLY basic description. I would encourage you to google “Statistical Process Control” for a more in depth description. Or scan the information on this website.

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    #171690

    Sridhar Sukumar
    Member

    A run chart is to observe the behaviour of data over a period of time. (X axis will be always time). if  we add a 3 standard deviation , median line to run chart it becomes a control chart.This would tell whether the process is in control or not

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    #171744

    Hardik
    Participant

    hi MDSB & sridhar , thanks a lot for helping me these concepts , do you know any nice stats basic web site ,
    If possble can i have your email so that i ask questions directly .
    Regards
    Rahul

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    #171747

    Julian
    Participant

    If you want to really learn more about SPC, you might try reading the following book.  It is invaluable and explains this science in excellant detail.  Although it was written for healthcare, you will learn about the different types of control charts, etc.  “Statistical Process Control for Health Care” by Marilyn K. Hart and Robert F. Hart.  They also teach a course on it!

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    #171761

    Ron
    Member

    If you want a book on SPC go to the master
    Donald Wheeler “Understanding statistical Process Control”

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    #171779

    Fake Engine Lady
    Participant

    Please submit details.
    How to purchase this book?

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    #171789

    Golfer
    Participant

    To purchase Understanding Statistical Process Control by Wheeler, try the iSixSigma web site or a book store!

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    #171928

    Mundorff
    Member

    A good basic free resource is the NIST Sematech Engineering Statistics Handbook at http://www.itl.nist.gov/div898/handbook/index.htm.
    It is also downloadable as a standalone executable.
     

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    #172279

    chuckAL
    Participant

    I am surprised nobody mentioned the book by Montgomery published by Wiley?  This is the book used in most colleges and universities in the US to teach SQC.  Although the book is far from being perfect (no book is) for my money, I would look there first.  He came up with another editon (6th?) recently.
     

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    #176289

    Sridhar Sukumar
    Member

    I Agree,  the statistics by Montgomery is one of the best books on stats.

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    #176292

    Jabber
    Participant

    The primary difference is when to use it.  Both are simply graphical depictions of some aspect of your process over time (ie both are time-series charts).  Both can readily show you if your process mean has shifted or if the variability has changed.  And both can indicate special cause.
    The run chart is used more often when you have fewer data points     (n < 25) or when out in the field collecting data for an initial assessement – plotting the run chart is relatively simple to do in a field environment…control charting requires more work, or a laptop.
    So if you are looking at your process in its environment and you need a quick and simple way to characterize its performance over time, use the run chart.  Or if you are dealing with smaller sample sizes (app. n<25).
    If you have access to software and sufficient data, use the appropriate CC.  It is a more powerful tool and often easier to create and interpret (when using software).
    My opinion.  Good luck.

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