Two-dimensional box plot

• Main Author: Phattrawan Tongkumchum
• Format: Article
• Language: English
• Published: Prince of Songkla University 2005-07-01
• Series: Songklanakarin Journal of Science and Technology (SJST)
• Subjects: two-dimensional box plot; bivariate graphical display; bivariate box plot; Tukey’s line
• Online Access: http://www.sjst.psu.ac.th/journal/27-4-pdf/17-box-plot.pdf

In this paper we propose a two-dimensional box plot, a simple bivariate extension of the box plot and the scatter plot. This plot comprises a pair of trapeziums oriented in the direction of a fitted straight line, with symbols denoting extreme values. The choice for the fitted straight resistant line showing the relationship between the two variables is Tukey’s resistance line. The main components of the plot are an inner box containing 50% of the projection points of the observations on the fitted line, a median point inside the inner box, and an outer box that separates outliers. The two-dimensional boxplot visualises the location, spread, correlation and skewness of the data.