A quantile is a statistic that identifies the data that is less than the given value (ie that fall at or below a score in a distribution).
A quantile function will always rank the data before giving any output.
The quantile limits can be use to create equal-frequency bins
The most commonly used percentile is the median. Half of the data is below the median.
Cleveland’s formula on an ordered data set
<math> f_i = \frac{\displaystyle i-0,5}{\displaystyle n} </math>
where: