EMPLOYMENT PSYCHOLOGY 
certain point about this procedure is that nothing is known 
of the tested ability of the proved failures. They might 
make the same scores as the experts! No differentiation in 
test performance between experts and failures is proved. 
We may then conclude that the best way to choose sub- 
jects for testing is to select workers already known to be 
competent or incompetent, provided the extremes of ability 
as well as the middle ranges are available in sufficient num- 
bers, and provided the group is in other respects sufficiently 
homogeneous, or sufficiently large to make possible a statis- 
tical control of disturbing variables. 
Where the number of experienced employees is too few, 
or too uniform in ability to yield a sufficient range in the 
criterion of vocational success, measurement of new 
workers at the time of employment is indicated. Except 
for the disadvantage of protracting the investigation, this 
procedure will commend itself for the reasons already 
stated. Applicants should be hired for experimental pur- 
poses regardless of their test scores. 
GENERAL CONSIDERATIONS 
No man should take the tests under compulsion. If any- 
one fails to respond to persuasion, the investigator will do 
well to let the matter rest. When the Jthers have been 
tested, the obstinate person is apt to ask for an examination. 
Any person should be rejected as a subject who is already 
familiar with the tests or other measuring instruments. 
Occasionally a supervisor or other minor executive whose 
men are being examined will ask that he also be given an 
examination. The investigator will find it advisable to re- 
fuse all special requests, with the explanation that since the 
tests are still in the experimental stage and nothing is 
definitely known of their value, the scores will be meaning- 
less. 
The scores made by individual workers during the experi- 
mental period of test development and standardization 
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