Editing Five-number summary (section)

{{Short description|Set of descriptive statistics}}{{Refimprove|date=January 2013}}

The '''five-number summary''' is a set of [[descriptive statistics]] that provides information about a dataset. It consists of the five most important sample [[percentile]]s:
# the [[sample minimum]] ''(smallest observation)''
# the [[quartile|lower quartile]] or ''first quartile''
# the [[median]] (the middle value)
# the [[quartile|upper quartile]] or ''third quartile''
# the [[sample maximum]] (largest observation)

In addition to the median of a single set of data there are two related statistics called the upper and lower quartiles. If data are placed in order, then the lower quartile is central to the lower half of the data and the upper quartile is central to the upper half of the data. These quartiles are used to calculate the interquartile range, which helps to describe the spread of the data, and determine whether or not any data points are outliers.

In order for these statistics to exist, the observations must be from a [[univariate]] variable that can be measured on an ordinal, interval or ratio [[Level of measurement|scale]].