Quartiles Calculator based on Excel

quartile calculator

Quartiles Calculator is created as a web calculator for helping students practice various methods to find quartile of data set.A quartile is a statistical term that divides the data into four quarters. Why do we need quartiles in statistics? The main reason is to perform further calculations, like the interquartile range, which is a measure of how the data is spread out. The quartiles of data is represented as under :

  1. First Quartile(Q1)=((n+1)/4)th Term also known as the lower quartile.
  2. The second quartile or the 50th percentile or the Median is given as:  Second Quartile(Q2)=((n+1)/2)th Term
  3. The third Quartile of the 75th Percentile (Q3) is given as: Third Quartile(Q3)=(3(n+1)/4)th Term also known as the upper quartile.
  4.  The interquartile range is calculated as: Upper Quartile – Lower Quartile.

Quartiles Calculator

Quartile Calculator

How to use Excel or Google Sheet to calculate quartile?

Excel or Google Spreadsheet has a built-in QUARTILE function. Important to note that the data set must be arranged in ascending order. So, using the built-in function, you can use functions as under

Minimum Number=quartile(data_range,0)
First Quartile or Lower Quartile=quartile(data_range,1)
Second Quartile or Median=quartile(data_range,2)
Third Quartile or Upper Quartile=quartile(data_range,3)
Maximum Number=quartile(data_range,4)

Methods of Finding Quartile

Wikipedia has provided four methods . It is reproduced verbatim

Method 1

  1. Use the median to divide the ordered data set into two-halves.
    • If there is an odd number of data points in the original ordered data set, do not include the median (the central value in the ordered list) in either half.
    • If there is an even number of data points in the original ordered data set, split this data set exactly in half.
  2. The lower quartile value is the median of the lower half of the data. The upper quartile value is the median of the upper half of the data.

This rule is employed by the TI-83 calculator boxplot and “1-Var Stats” functions.

Method 2

  1. Use the median to divide the ordered data set into two-halves.
    • If there are an odd number of data points in the original ordered data set, include the median (the central value in the ordered list) in both halves.
    • If there are an even number of data points in the original ordered data set, split this data set exactly in half.
  2. The lower quartile value is the median of the lower half of the data. The upper quartile value is the median of the upper half of the data.

The values found by this method are also known as “Tukey’s hinges”; see also midhinge.

Please visit wikipedia page for 3rd and 4th methods

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