THE SCOPE OF PSYCHOLOGICAL TESTS 
201 
both the ability and the character necessary for success 
and who do succeed. Therefore, in spite of the fact that 
psychological tests do not suffice in the discovery of one of 
the two most important factors about applicants they 
nevertheless make it possible to eliminate those in 
dividuals who do not possess the other known factor. 
Thus they enable us to consummate a very great reduction 
in the number of possible errors, and to bring the process 
of selection much closer to the region of accuracy and 
certainty. 
The best and most authentic example of this process 
which has been obtained is that described in Chapter III. 
Here it was seen that a considerable number of inspectors 
who did not pass the tests but who were hired neverthe 
less were failures. This number corresponds to the first 
large class of those who have not the necessary ability, and 
who can be eliminated at the outset by means of the tests. 
Next, there was a group who passed the tests but who 
nevertheless failed. This group probably failed because 
did not possess the necessary moral qualities. Finally, 
there remained the group which succeeded and which 
Worked for a period of from one to four months at piece 
work production. This group undoubtedly possessed the 
necessary moral traits and ninety-four per cent of them 
bad passed the tests, showing that they had the necessary 
ability. This is a very good example of the practical scope 
a nd value of tests when applied to employment work, 
ev en though that scope does not embrace the discovery of 
every fact about an individual which the employment 
office would like to know. (Moreover, the example is an 
exceptionally valuable one because both those who did not 
pass the tests and those who did were hired. Therefore, it 
became possible to show the enormous amount of work