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interquartile range

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  • #43830

    slimboy
    Member

    Hello
    Does anyone know how interquartile range compares to standard deviation.
    ie normal data calc mean ,measure of dispersion is stdev
    ie non-normal data calc median ,measure of dispersion is interquartile range
    thanks
    slimboy

    0
    #139584

    Darth
    Participant

    They are different.  The s.d. uses all the data to come up with a value.  The interquartile range is merely the difference between the 25th percentile value and the 75th percentile value.  This is usually associated with a box plot.

    0
    #139603

    slimboy
    Member

    Thanks Darth,
    What iam investigating is whether i should use interquartile range in a safety stock calculation instead of stdev when the distribution is not normal.
     
    Cheers
    slim

    0
    #139604

    Darth
    Participant

    Another thought is to fit the proper distribution to your data and use the s.d. for that curve to do your calculations and figure out your service level coverage.

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