SELECTION OF EXAMINATIONS 77
What, then, are the characteristics of a good test? And
where should the investigator search for suitable test
materials?
PRINCIPLES GOVERNING THE SELECTION AND
CONSTRUCTION OF TESTS
Objectivity. Foremost among the characteristics of a
scientific test is that it yields objective measures. Opinion,
individual judgment, and the personal equation of the
examiner who gives or scores the test should be reduced to
a minimum.
Research procedure in vocational selection has for its
purpose the provision of something better than mere
hunches or unanalyzed general impressions as a basis
for decisions and recommendations. The outstanding characteristic
 of the unscientific methods is their lack of objectivity.
 An interviewer who relies on subjective impressions
 or indefinable intuitions is dependent upon his alertness,
 his previous experience, and his social sensitivity, He
never knows when or how much he can trust his hunches.
Moreover, interviewers differ widely in their ability to arrive
at a fair estimate of an applicant through general impression.
 Their judgments tend to be at variance because of
personal prejudices, differences in ability to judge, and
failure to agree upon the vital point most essential for the
job. A few rare employment interviewers seem to be very
successful although relying on their unanalyzed subjective
impressions. But no business concern wishes to be dependent
 upon a rarely gifted person who cannot readily be replaced.
 The purpose of the investigator is to bring to light
the abilities and characteristics of a worker which the successful
 interviewer judges in the applicant, and to measure
them accurately by a method which can then be used with
equal success by any carefully trained examiner. For intuitive
 opinion he substitutes objective tests.