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What is Interquartile Range

  • 14-08-2015 10:02am
    #1
    Catherine43
    Registered Users, Registered Users 2 Posts: 1 ✭


    What is Interquartile Range...What is the use of finding it...

    for a set of data : 5, 11, 43, 23, 21....What is the IQR...

    I dont want any reference links as i already got it from an online IQR calculator in easycalculation site
    Need detailed explanation
    Tagged:


Comments

  • #2
    MathsManiac
    Registered Users, Registered Users 2 Posts: 1,595 ✭✭✭MathsManiac


    It is a measure of spread in a data set, so its purpose/usefulness is akin to that of the standard deviation.

    Typically, if two data sets had the same median but one had a bigger IQR than the other, then the one with the bigger IQR is a more spread out set of data (or equivalently, the one with the smaller IQR is a more bunched up set of data).

    Correspondingly, I could say this:
    Typically, if two data sets had the same mean but one had a bigger standard deviation than the other, then the one with the bigger standard deviation is a more spread out set of data (or equivalently, the one with the smaller standard deviation is a more bunched up set of data).

    In many ways it's a much more intuitive measure of spread than the standard deviation is. It's the range of the middle half of the data. That is, if you discard the top quarter and the bottom quarter, it's the range of what's left.


  • #3
    Mwalimu
    Registered Users, Registered Users 2 Posts: 42 ✭Mwalimu


    Think of the set of data divided into four parts. The lower quartile represents a value (not necessarily a data point in the given set) which has 25% of the data below it. The upper quartile is a value which has 25% of the data above it. So, the IQR represents the spread of data between these two values. As MathsManiac says, it gives the spread of the middle half of the data.

    Catherine43 wrote: »
    What is Interquartile Range...What is the use of finding it...

    for a set of data : 5, 11, 43, 23, 21....What is the IQR...

    I dont want any reference links as i already got it from an online IQR calculator in easycalculation site
    Need detailed explanation


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