Chamnein Choonpradub and Don McNeil

pp. 649 - 657

Abstract

Invented by Spear in 1952 and popularized by Tukey in 1977, the box plot is widely used for displaying
and comparing samples of continuous observations. Despite its popularity, it is less effective for showing
shape behaviour of distributions, particularly bimodality. Using robust estimators of data skewness and
kurtosis to classify the distribution into categories, we suggest a simple enhancement for indicating bimodality,
central peakedness, and skewness. We also suggest a new graphical method for displaying confidence intervals
when comparing several samples of continuous data.

Keywords

• box plot
• bimodality
• peakedness
• skewness
• kurtosis
• graphing confidence intervals
• multiple comparisons