Decile

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.

Special usage: The decile 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.