The method of definition distribution Fisher-Tippeta parametres of final volume population (Ас, Вс, Сс) under the selective data of the average stress is offered in the given work. Average values of parametres (Ас, Вс, Сс) thus is recommended to use at repeated modelling. Thus the Ас, Вс, Сс received is recommended to use average values of parametres at repeated modelling.

Keywords: the selective data, stress, Fisher-Tippet distribution, population, modeling.