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Decile

Quantile dividing data into 10 equal parts

Wikipedia contributorsAdapted for Fathomly · View authors
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Source updated September 16, 2026

In descriptive statistics, a decile is any of the nine values that divide the sorted data into ten equal parts, so that each part represents 1/10 of the sample or population. A decile is one possible form of a quantile; others include the quartile and percentile. A decile rank arranges the data in order from lowest to highest and is done on a scale of one to ten where each successive number corresponds to an increase of 10 percentage points.

01Decile mean

A moderately robust measure of central tendency, known as the decile mean, can be computed by making use of a sample's deciles D_{1} to D_{9} (D_{1} = 10th percentile, D_{2} = 20th percentile and so on). It is calculated as follows:

DM={\frac {\sum _{i=1}^{9}D_{i}}{9}}

Apart from serving as an alternative for the mean and the truncated mean, it also forms the basis for robust measures of skewness and kurtosis, and even a normality test.

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This article is adapted from the Wikipedia article “Decile”, written by its contributors and licensed under CC BY-SA 4.0. Fathomly has changed the layout, removed citation markers, navigation and maintenance notices, and adjusted punctuation. This adapted version is shared under the same license. For references, see the original article.

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Summary statistics

In descriptive statistics, summary statistics are used to summarize a set of observations, in order to communicate the largest amount of information as simply as possible. Statisticians commonly try to describe the observations in a measure of location, or central tendency, such as the arithmetic mean a measure of statistical dispersion like the standard mean absolute deviation a measure of the shape of the distribution like skewness or kurtosis if more than one variable is measured, a measure of statistical dependence such as a correlation coefficient A common collection of order statistics used as summary statistics are the five-number summary, sometimes extended to a seven-number summary, and the associated box plot.

Socioeconomic decile

In the New Zealand education system, decile was a key measure of socioeconomic status used to target funding and support schools. In academic contexts the full term "socioeconomic decile" or "socioeconomic decile band" was used.