Appendix: The EVA Methodology

Extreme Value Analysis (EVA) is based on the Extremal Types theorem, which states that if samples are taken from a well behaved, arbitrary probability distribution, the resulting extremes (min / max) can be approximated and parameterised by one of 3...

EVA in IMS fits a Gumbel distribution to the data. This a special form of the GEV distribution with the shape parameter taken to be 0. The Gumbel distribution is preferred to the generalized GEV as it gives narrower confidence bounds (one parameter ...

The purpose of Goodness of Fit tests are to investigate how well a given sample of data approximates a given probability distribution. Reliable prediction of the whole system’s maximum wall loss strongly depends on the fitted model’s quality. It is...

The extrapolation methods aim at statistical inference about extreme wall loss/pit depth on the whole HX (or stratum), or on the not inspected part. For this purpose, two methods are used, the first is the return-level   method, the other...