The range

In statistics, the range is a measure of the total spread of values in a quantitative dataset. Unlike other more popular measures of dispersion, the range actually measures total dispersion (between the smallest and largest values) rather than relative dispersion around a measure of central tendency.

Interpreting the range

The range is interpreted as "the overall dispersion" of values in a dataset or, more literally, as the "difference between the largest and the smallest value" in a dataset. The range is measured in the same units than the variable of reference and, thus, has a direct interpretation as such. This can be useful when comparing similar variables but of little use when comparing variables measured in different units. However, because the information the range provides is rather limited, it is seldom used in statistical analyses.

For example, if you read that the age range of two groups of students is 3 in one group and 7 in another, then you know that the second group is more spread out (there is a difference of seven years between the youngest and the oldest student) than the first (which only sports a difference of three years between the youngest and the oldest student).

Properties

The range is a descriptive statistic which identifies the total spread of values in a dataset.
Although the range can stand alone as a descriptive statistic, it may also be loosely associated with the mid-range (a measure of central tendency).

Editor

Jose D PEREZGONZALEZ (2012). Massey University, Turitea Campus, Private Bag 11-222, Palmerston North 4442, New Zealand. (JDPerezgonzalez).

Want to know more?

Wiki of Science - Descriptive statistics: This Wiki of Science page provides access to more descriptive statistics.
Wiki of Science - Range (calculation): This Wiki of Science page provides you with the tools to calculate the range.