####  Quantiles (p)

We can generalize to any proportion $p$.

The $p-$quantile denoted $q_p$ is a value which divides the samples such as a proportion $p$ of the individuals are below the quantile. 

The median is $q_{\frac{1}{2}}$. The lower quartile is $q_{\frac{1}{4}}$ and the upper quartile is $q_{\frac{3}{4}}$.