Alpha Quantile

A quantile of order alpha with 0 <= alpha <= 1 is a number Q, which separates the sorted parameter values such that:

Example:

The 25% quantile Q_.25 is the number where 25% of the parameter values are smaller or equal than Q – and 75% of the parameter values are bigger than the stated number Q.

This statistical attribute is used e.g. with the normal distribution.

See: http://en.wikipedia.org/wiki/Quantile