Box and Whisker Plot

 

It is the visual way to show the five number summary. It is the graphical representation of the data and displays a five number summary based on the minimum value, lower quartile, median, upper quartile and the maximum value. The left vertical line of the box is first quartile (Q1) and the right vertical line shows third quartile (Q3). The box contains middle 50% of the value. The lower 25% of the data is represented by the line .i.e. whisker connecting minimum value and first quartile (Q1). The upper 25% of the data are represented by the whisker connecting the largest value and the third quartile (Q3). If the middle vertical line of the box is near to the right vertical line of the box then the data is right skewed. If it is in the middle of the box then the data is symmetric.

Example 1: Draw a box-and-whisker plot for the data set {3, 7, 8, 5, 12, 14, 21, 13, 18}.

Minimum: 3, Q₁ : 6, Median: 12, Q₃ : 16, and Maximum: 21.

Example 2: Draw a box-and-whisker plot for the data set {3, 7, 8, 5, 12, 14, 21, 15, 18, 14}.

Minimum: 3, Q₁: 7, Median: 13, Q₃: 15, and Maximum: 21.