THE SCOPE OF PSYCHOLOGICAL TESTS 209 
select tests which are appropriate; (2) a preliminary ex 
periment with a large group of workers engaged in the 
same kind of work in order to determine the value of the 
tests selected and the standards which shall be used; 
(3) an objective or impersonal measure of the work done 
by the members of the group in order to provide a reliable 
and accurate basis upon which to compare both the in 
dividuals and their performances in the tests. The diffi 
culty of meeting these three conditions makes it impossible 
to apply tests intelligently to executives in the higher 
and more specialized positions. However, there is a vast 
and ever growing field where these conditions exist and 
■where tests may therefore be readily applied, and some 
indications of the scope of this field have been given in the 
previous chapters. 
With regard to the qualitative scope of tests, or their 
degree of reliability, it has been seen that their chief value 
lies in detecting the innate or acquired mental ability of 
the individual. Tests do not reveal the moral qualities 
and in this sense their value is limited. But even with 
this limitation, they make it possible to select the man 
who is most likely to possess them. For, as has been seen, 
the moral traits are relative, and depend in large measure 
upon the ability of an individual to make good; and this 
ability does come within the scope of tests to determine. 
Finally, the knowledge which tests can give us about the 
abilities of individuals offers, for the first time, a scientific 
or objective basis upon which to use the powerful stimulus 
of suggestion. By the use of suggestion, much can be done 
to arouse and to create the moral qualities which are de 
sirable in a worker and which will make the worker not 
only more valuable to the industry but to himself.