EMPLOYMENT PSYCHOLOGY 
It has been customary to draw various lines of distinction 
between psychological tests and psychological experiments. Some 
of these distinctions have broken down in practice. It is not 
strictly correct to state that a test dispenses with the typical 
precautions in control of conditions deemed essential in a labora- 
tory experiment; nor that only the experiment utilizes instruments 
of precision. Nor is it always strictly true that an experiment is 
performed to try out an hypothesis and establish a generalization 
while a test is limited in its purpose to the measurement of the 
individual. Terman (186) in his presidential address before the 
American Psychological Association effectually disposed of that 
tradition by assembling the general principles of psychology which 
have been ‘developed by means of research with tests. 
In the foregoing chapter several features of a good voca- 
tional test were outlined. It should be simple in conception 
and operation. It should be constructed so as to yield an 
objective quantitative measure which does not vary with 
the person who administers or scores it. Its material, the 
conditions under which it is given, the directions, and the 
method of scoring should be rigidly specified and adhered to, 
so that scores made by persons examined at different times 
and places will be comparable. It should be built on the 
theory that it measures one or more of the abilities neces- 
sary to the job. It should have an apparent relevance to 
the job requirements to insure the applicant’s interest. 
Chapter V discusses the ways of arriving at the abilities 
which the tests should aim to measure. In constructing a 
test for one of these abilities, the investigator will find it 
profitable to refer to the sources of test material listed in 
Chapter VI. He will also find it highly worth while to con- 
sult all relevant material on test construction and applica- 
tion gathered by other psychologists, especially where they 
have studied the same or similar vocations. Above all, he 
should hesitate to develop a new test if he can find one 
already available. Unless he makes a decided improvement 
on an existing test he will do little more than add to the 
growing profusion of insufficiently evaluated and hence use- 
less psychological tests. 
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