# Tag Archives: Percentile

## Percentiles

For a random variable $X$, the 100pth percentile is the unique value $\pi_p$ such that $\Pr(X \le \pi_p)=p$.  A qth quantile is a value $\pi_q$ such that $\Pr(X \le \pi_q)=q$.  For example, if $F(1120) = 0.2$, we can either say 1120 is the twentieth percentile or 1120 is the one-fifth quantile.