Boxplots

Before viewing this page, it would be helpful to learn how to calculate Quartiles.

Box-and-whisker plots are graphs showing five-number summary statistics (lowest score, 1st quartile, median or 2nd quartile, 3rd quartile, highest score) as follows:

Did You Know That...?

People from the Netherlands (Dutch people) are the world's tallest people with an average height of 1.85 metres. As a nation, people from Japan are the world's shortest people with an average height of 1.63 metres.

Example - Boxplot of Dutch Jeans' Sizes

The waist to ankle lengths (in cm) for 15 Dutch men are listed below. By first calculating the five-number summary, show this information as a boxplot.

Ordered Data (from smallest to largest) -
90, 91, 92, 94, 97, 98, 98, 100, 100, 105, 106, 107, 110, 111, 112


Answer:
n = 15
Lowest Score = 90 cm

1st Quartile= (n + 1) ÷ 4= (15 + 1) ÷ 4= 4th man= 94 cm
Median= (n + 1) ÷ 2= (15 + 1) ÷ 2= 8th man= 100 cm
3rd Quartile= (n + 1) ÷ 4 × 3= (15 + 1) ÷ 4 × 3= 12th man= 107 cm

Highest Score = 112 cm

Boxplot diagram

Question - Boxplot of Japanese Jeans' Sizes

The waist to ankle lengths for 11 Japanese men are listed below. By first calculating the five-number summary, show this information as a boxplot.
Ordered Data (in cm) - 70, 71, 73, 75, 75, 78, 79, 82, 85, 86, 88