Decile Explained

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.^[1] A decile is one possible form of a quantile; others include the quartile and percentile.^[2] 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} = 10^th percentile, D _{2} = 20^th percentile and so on). It is calculated as follows:^[3] DM = (\sum ^{9} _{i =1} 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.^[4]

See also

• Summary statistics
• Socio-economic decile (for New Zealand schools)

Notes and References

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2. .
3. Sohel . Rana . Md. . Siraj-Ud-Doulah . Habshah . Midi . A. H. M. Rahmatullah . Imon . Decile mean: A new robust measure of central tendency . Chiang Mai Journal of Science . 39 . 3 . 478–485 . 2012 .
4. Md. . Siraj-Ud-Doulah . An Alternative Measures of Moments Skewness Kurtosis and JB Test of Normality . Journal of Statistical Theory and Applications . 20 . 2 . 219–227 . 2021 . 10.2991/jsta.d.210525.002. free .