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Standard Deviation Vs Variation

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  • #28222

    Tom Lee
    Member

    Hi all
    What I really want to know is the exact difference meaning between Standard Deviation and Variation. Standard deviation denotes the average distance from the mean, and variation denotes it’s square amount. What’s the main reason we control the variance rather than Standard deviation although Standard deviation give us easy- to- understand numeric answer because it tells how far from the mean.
    And why for 6 sigma activity why we control the variance not standard deviation?

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    #69965

    Ken K.
    Participant

    The standard deviation is a measure of variation, usually applied to normal distributions, although it is also defined to be the square root of the second moment of any distribution.
    The standard deviation is simply the square root of the variance. They are one-one. For some circumstances, such as linear combinations of normal variates, the variance is easier to work with (the variance of a sum is the sum of the variances). For other circumstances, such as a discussion about the “width” of the distribution, the standard deviation is easier to work with, since it is in the same units as the random variable itself.

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    #69970

    Dee Umbass
    Participant

    I personally like working with variation better. I find it easier and a lot quicker to reduce a lot.Dee

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    #69984

    Terry Krueger
    Member

    Two things
    Squaring a number eliminates negatives
    Squaring also produces a nonlinear curve (like chi-square)
    e.g.
    2>4
    4>16
    16>256
    and therefore visibility increases exponentially.

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