Range

The range is the difference between the largest and smallest value in a dataset — the simplest single number describing how spread out the data is.

Subtract the minimum from the maximum and you have the range. It captures the full width that the data occupies, from one extreme to the other. Because it depends only on the two end values, it is quick to compute and easy to understand, though it tells you nothing about how the values in between are distributed.

How range works in a chart

Range governs how much vertical (or horizontal) space a chart must cover: the value axis has to stretch at least from the smallest to the largest data point, so a wider range demands a taller or more compressed axis. It also shapes a box plot, whose whiskers typically reach toward the minimum and maximum, making the range visible as the full extent of the drawing. One caution: a single extreme outlier inflates the range dramatically, since it moves the maximum or minimum on its own.

A concrete example

Suppose daily high temperatures over a week are 12, 15, 14, 18, 11, 16 and 13 degrees. The largest is 18 and the smallest is 11, so the range is 18 − 11 = 7 degrees. That single number says the week's highs varied across a 7-degree band. If one freakishly hot day of 30 degrees were added, the range would jump to 30 − 11 = 19 — showing how one extreme value can dominate this measure.

Related terms

Range is the crudest measure of spread; variance gives a fuller picture by accounting for every value's distance from the average. The data's span sets the bounds of the value axis, and in a histogram the overall range is sliced into bins. See spread in action in the histogram guide.