2D Box Plots

In Box Plots (this term was first used by Tukey, 1970), ranges or distribution characteristics of values of a selected variable (or variables) are plotted separately for groups of cases defined by values of a categorical (grouping) variable. The central tendency (e.g., median or mean), and range or variation statistics (e.g., quartiles, standard errors, or standard deviations) are computed for each group of cases, and the selected values are presented in the selected box plot style. Outlier data points can also be plotted (see Outliers and extremes).

Box plots can be specified to display the desired variability data using Whiskers, Boxes, Box-Whiskers, Columns, or High-Low Close (a type of whisker display) formats. Multiple box plots of a single box plot variable can be produced by the categories of a grouping variable (see Methods of Categorization), and function fits can be applied to the resulting series of box plots (see 2D Fit Lines). Single or multiple box plot variables can be selected.

See also, Graphs - Scatterplots w/Box Plots, Graphs - 2D Box Plots,  Graphs - Categorized Box Plots, and the Conceptual Overview for 2D Box Plots.