ABSTRACT
F(x) = exp [– exp {– (x – a)______b}] (1.1) In this model, F(x) is the probability distribution function, also known as distribution function or more commonly, cumulative frequency. a and b are the two parameters of the model: a is the location parameter and b is the scale parameter. The probability of observing an annual event greater than the value x is in this case p(x) = 1 – F(x): this statistical quantity is called the probability of exceedance or exceedance probability.
