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    tomma's Avatar
    tomma Posts: 2, Reputation: 1
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    #1

    Dec 19, 2008, 03:01 AM
    Standard Deviation vs Variance
    Why is it that "Unlike standard deviations variances can be added together"
    harum's Avatar
    harum Posts: 339, Reputation: 27
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    #2

    Jan 9, 2009, 07:47 PM

    Standard deviation is a square root of variance. If you add two or more random variables than variance of their sum is the sum of their variances. You can not say the same about the standard deviations.
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