Understanding of Boxplot

A Boxplot is a method for graphically depicting a summary of a set of numbers or in other words, a 5-number summary of a set of data.

The 5-number summary includes Minimum(min), 1st Quartile(Q1), Median, 3rd Quartile(Q3), and Maximum(max) from the numerical dataset. Let’s understand with an example. we have the following set of numbers

[25, 35, 37, 38, 29, 30, 34, 35, 28, 29]

Step-1: Order the data in ascending order (smallest to largest)

[25, 28, 29, 29, 30, 34, 35, 35, 37, 38]

Step-2: Find the Median.

Median = (30+34)/2 = 32

Step-3: Find Quartiles

1st Quartile (Q1): Median of data points to the left of the median

[25, 28, 29, 29, 30] → Q1 = 29

3rd Quartile (Q3): Median of data points to the right of the median

[34, 35, 35, 37, 38] → Q3 = 35

Step-4 : Find the Minimum(min) and Maximum(max) numbers from data

min = 25 & max = 38

So, the Five-Number summary is: 25, 29, 32, 35, 38

Graphical Representation of 5-Number Summary