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 char- 
acteristic of the unscientific methods is their lack of ob- 
jectivity. An interviewer who relies on subjective impres- 
sions or indefinable intuitions is dependent upon his alert- 
ness, 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 impres- 
sion. 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 depen- 
dent upon a rarely gifted person who cannot readily be re- 
placed. The purpose of the investigator is to bring to light 
the abilities and characteristics of a worker which the suc- 
cessful 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 in- 
tuitive opinion he substitutes objective tests.