The authors provide a review of statistical algorythms used in selection of items when constructing scales. The simplest algorythms which can be used by psychologists in the absence of a computer are described in sufficient detail. Some modifications are suggested which allow to even more simplify the procedure and make it more convenient for a practicing psychologist. Apart from the perspective of using such "manual" algorythms the authors tell the reader that there may appear in the nearest future a computer-based bank of psychodiagnostical data and of psychometric programmes which will make it possible for all psychologists supplying their data to the bank to employ powerful computer algorythms realized on big contemporary computers.