Fréchet distribution


The Fréchet distribution, also known as inverse Weibull distribution, is a special case of the generalized extreme value distribution. It has the cumulative distribution function
where α > 0 is a shape parameter. It can be generalised to include a location parameter m and a scale parameter s > 0 with the cumulative distribution function
Named for Maurice Fréchet who wrote a related paper in 1927, further work was done by Fisher and Tippett in 1928 and by Gumbel in 1958.

Characteristics

The single parameter Fréchet with parameter has standardized moment
defined only for :
where is the Gamma function.
In particular:
The quantile of order can be expressed through the inverse of the distribution,
In particular the median is:
The mode of the distribution is
Especially for the 3-parameter Fréchet, the first quartile is and the third quartile
Also the quantiles for the mean and mode are:

Applications

However, in most hydrological applications, the distribution fitting is via the generalized extreme value distribution as this avoids imposing the assumption that the distribution does not have a lower bound.