The range provides an indication of statistical dispersion, or how spread-out the data are. It is measured in the same units as the data. Since it only depends on two of the observations, it is a poor and weak measure of dispersion except when the sample size is large. A better measure of the dispersion of the data is the variance or the standard deviation. The range, however, is much simpler to calculate.

The midrange point, that is, the point halfway between the two extremes, is an indicator of the central tendency of the data, or the "average" value of the data. Again it is not a particularly good measure of central tendency for small samples; other more robust measures of the "average" of the data are the mean and the median.

1. This definition is based on the Wikipedia definition of the range [disclaimer].