Measures of Dispersion

These statistics describe how the data varies or is dispersed (spread out).

The two most commonly used measures of dispersion are the range and the standard deviation. Rather than showing how data are similar, they show how data differs (its variation, spread, or dispersion).

Quoting both a measure of central tendency and the relevant measure of dispersion for one set of data gives a much better picture of the data than quoting one alone.

Other measures of dispersion that may be encountered include the Interquartile range (IQR) and the Semi-interquartile range (SIQR).