Finding the median and quartiles for grouped data

Last updated: 15/11/2023
Contributor: Raj Bobal
Finding the median and quartiles for grouped data
Main Subject
Key stage
Category
Statistics and probability: Analysing data
Inside
Includes answers
Resource type
Worksheet

A clear description of how to find the median and quartiles of grouped data.

Median for Grouped Data

The median for grouped data can be found either by interpolation or by using a formula.
The formula is
Median =LB+w((1/2 n-∑ f_b)/f_m )
where
        LB is the lower boundary or limit of the class containing the median
        w is the width of the median class interval
        n is the total frequency, or the number of values
        ∑ f_b is the number of values below LB
        f_m is the number of values containing the median

Median for Grouped Data

The median for grouped data can be found either by interpolation or by using a formula.
The formula is
Median =LB+w((1/2 n-∑ f_b)/f_m )
where
        LB is the lower boundary or limit of the class containing the median
        w is the width of the median class interval
        n is the total frequency, or the number of values
        ∑ f_b is the number of values below LB
        f_m is the number of values containing the median

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Clear precise explanation for this most difficult [for some] topic. Thanks

28/10/2016

Clear precise explanation for this most difficult [for some] topic. Thanks

28/10/2016