In statistics, the generalized Pareto distribution (GPD) is a family of continuous probability distributions. It is often used to model the tails of another distribution. It is specified by three parameters: location μ {\displaystyle \mu } , scale σ {\displaystyle \sigma } , and shape ξ {\displaystyle \xi } . Sometimes it is specified by only scale and shape and sometimes only by its shape parameter. Some references give the shape parameter as κ = − ξ {\displaystyle \kappa =-\xi \,} .
With shape ξ > 0 {\displaystyle \xi >0} and location μ = σ / ξ {\displaystyle \mu =\sigma /\xi } , the GPD is equivalent to the Pareto distribution with scale x m = σ / ξ {\displaystyle x_{m}=\sigma /\xi } and shape α = 1 / ξ {\displaystyle \alpha =1/\xi } .