Definition:Percentile

Definition
Let $D$ be a finite collection of $n$ data regarding some quantitative variable.

Let $D$ be divided into precisely $99$ classes.

A $P$th percentile is a value in the interval defined by the $P$th class such that:


 * $\dfrac P n$ of the data in $D$ fall at or below the value chosen;


 * $1 - \dfrac P n$ of the data in $D$ fall at or above the value chosen.

Arbitrarily more precise definitions may be contrived as necessary to define a unique percentile for a given study.

Also see

 * Quartile
 * Decile