Box and whisker plot

A graph for displaying the distribution of a numerical variable, usually a measurement variable.

Box and whisker plots are drawn in several different forms. All of them have a "box" that extends from the lower quartile to the upper quartile, with a line or other marker drawn at the median. In its simplest form, one whisker is drawn from the upper quartile to the maximum value, and the other whisker is drawn from the lower quartile to the minimum value.

Box and whisker plots are a particularly useful way of comparing the distribution of a numerical variable for two or more categories, or a category variable, by displaying side-by-side box and whisker plots on the same scale. Box and whisker plots are particularly useful when the number of values to be plotted is reasonably large.

Box and whisker plots may be drawn horizontally or vertically.

Example

The actual weights of random samples of 50 male and 50 female students enrolled in an introductory statistics course at the University of Auckland are displayed on the box and whisker plot below.

Alternatives: box and whisker diagram, box and whisker graph, box plot

Curriculum achievement objectives references

Statistical investigation: Levels 5, 6, 7, 8

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