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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 (grouped in 4) and percentile (grouped into 100). Deciles are used heavily in government data publications. A typical example of deciles in use is the Household Income dataset as presented below.

GroupDecileAverage gross weekly household income (£)
Lowest 10%1130
Second decile group2250
Third decile group3340
Fourth decile group4440
Fifth decile group5550
Sixth decile group6670
Seventh decile group7820
Eigth decile group81,010
Ninth decile group91,280
Highest 10%102,280