Box plots are used to represent the 5 data items listed below graphically, which are:

  • Lowest value in the dataset
  • Lower Quartile (LQ)
  • Median
  • Upper Quartile (UQ)
  • Highest value in the dataset.

A nice feature of box plots is that the length of the box gives you the interquartile range (IQR). That’s the region where the bulk of the data is found.

Below are 3 examples of how to draw a box plot. Examples 1 and 2 use sets of data and example 3 uses a cummulative frequency diagram.

Example 1

Example 2

Example 3

By Substitution when Elimination Fails
Frequency Polygons