_ EMPLOYMENT PSYCHOLOGY 
skilfully handled, even those employees who separate them- 
selves from the company are more likely to want to return 
later on. They go as friends rather than as enemies. 
Most employment offices keep statistics on causes of leav- 
ing. Data from the records of casual interviews are worse 
than useless. They are misleading. But statistics gathered 
from conscientious and skilful interviews may throw val- 
uable light on conditions in the plant, on the personality of 
foremen and supervisors, and on employee attitudes which 
modify the validity of test predictions. 
MAINTENANCE 
It is a responsibility of the investigator to assure himself 
that so long as the tests are used they are administered 
strictly in the manner outlined in his report and that no 
modifications are made which are not justified scientifically. 
He may even have to assure himself that the tests are being 
used at all, as there is a natural tendency to revert to former 
methods of making off-hand judgments, or for examiners to 
estimate the applicant’s score without completely carrying 
out the test procedure. 
Modifications of procedure and standards. The investi- 
gator must also, from time to time, check the test results 
against the criterion of success to find whether the tests are 
still efficient or whether changing circumstances call for 
modifications in procedure or in critical scores. Conditions 
of the labor market or of employment within the plant some- 
times change the predictive accuracy of tests, so that fre- 
quent checks should be made on their efficiency. Thus, if a 
supervisor uses special incentives on those who have passed 
the tests, on the assumption that these new employees will be 
so successful that it is especially worth while trying to 
develop them and hold them, a different sort of person may 
be led to apply for the position. Moreover, some of those 
who failed to make good under previous conditions might 
have succeeded if this new type of supervision had been 
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