228 
EMPLOYMENT PSYCHOLOGY 
at this point that the difference between valuable and use 
less tests will be discovered or overlooked. 
The following occurrence will help to show the impor 
tance of preliminary trials. A set of trade tests for tool 
makers developed and standardized in a certain industry 
were installed in the employment office of another com 
pany. After they had been in use for a few months, three 
of the former expert tool makers of that company who had 
left to work with another concern returned and asked for 
their old positions. They were given the trade tests and 
two of the men failed to obtain even an apprentice rating 
while the third made a low journeyman’s rating. All of 
these men had been considered among the best in the shop, 
and their failure in the tests therefore aroused the sus 
picions of the employment manager. He decided to give 
the tests to the seventy-four tool makers in that particular 
shop, and out of that number forty-seven failed completely, 
twenty-one were rated as apprentices, and only six ob 
tained a journeyman’s rating. An analysis of the causes 
for this low correlation showed that the methods pursued 
in this shop were slightly different from those used in the 
shop where the tests had originated. Not until the tests 
were actually tried out under the new circumstances did 
the real nature of this difference become apparent. 
Trades and occupations are different in almost every 
industry to-day, and the practical significance of these dif 
ferences for employment will be revealed only by means of 
experiments and actual trials such as have been described. 
Valuable as trade tests are, it must not be forgotten 
that they are limited in their scope. As their name in 
dicates, they apply only to trades; that is, to occupations 
which involve a certain body of standard knowledge such 
as may be acquired during the course of an apprentice