200 EMPLOYMENT PSYCHOLOGY Possessed of the necessary ability. Possessed of the nec essary moral traits. Without the nec essary ability. Without the nec essary moral traits. The four possible combinations are as follows: (i) Those with the necessary technique and also the necessary moral traits. (2) Those with the necessary ability but without the necessary moral traits. (3) Those without the neces sary ability but with the necessary moral traits. (4) Those without the necessary ability and without the neces sary moral traits. Now, it will be seen that psychological tests, by being able to discover and measure ability or technique, imme diately make it possible to reduce the number of possible mistakes in selection by fifty per cent. By means of tests we are enabled, in the first place, to separate those who have the requisite ability from those who do not, regard less of the existence of the moral qualities. Therefore, the large number of applicants who have not the necessary ability to succeed at the particular job in question are rejected at once. Those who have the necessary ability may now be divided into two classes, those who have the necessary moral traits and those who have not. Because psychological tests cannot definitely discover the presence and degree of the moral qualities, the psychological exam iner is likely to recommend both of these groups for work. Of the number, some will undoubtedly fail because even though they have the requisite ability they lack the neces sary moral traits. There remain, then, those who have