Abstract
The return period is widely used on probability papers which are essential tool in the analysis of extreme values and/or dimension effect (the so-called size effect). Several considerations are indispensable in the application of the tool, however, because it requires sometimes uncertain extrapolation on the probability paper for extreme values. The problems are illustrated with corrosion pit depth data which are distributed doubly exponentially. Then a new analyzing method is proposed in connection with correct application of the return period for recognizing a reliable size effect. The possible usage of the first asymptotic distribution of the smallest values is also suggested in corrosion and its related field.
