CHOICE OF WORKERS TO BE STUDIED 53 
accumulate a sufficient number of cases of new employees. 
Moreover, with old employees the criterion of success may 
be obtained immediately, whereas nothing can be known 
about the newly hired workers until they have been at 
work for a considerable period of time. Meanwhile interest 
in the investigation may grow cold. 
In testing old employees it is important to avoid the 
measurement of technical training acquired since entering 
the service of this company. If, however, some of the 
tests are shown to measure abilities acquired by experience 
on this job, they may nevertheless be used on future ap- 
plicants on the assumption, subject to verification, that an 
applicant who comes to the firm already well equipped with 
these abilities, regardless of when or where he acquired 
them, will be more acceptable because he will require a 
shorter period of training than one who lacks these abilities. 
Difficulties in this regard will be diminished if the in- 
vestigator uses only newly hired workers as subjects and 
compares their standings in tests as obtained at the time of 
application with their vocational success as later demon- 
strated, or if he uses old employees as subjects but elimi- 
nates from his tests material of a technical or informational 
sort. 
Scott (165) suggested the inclusion among a group of 
applicants of a “ringer” whose identity is unknown to the 
investigator. The ringer is known by the management to be 
either an exceptionally good worker or an exceptionally poor 
one; and it is assumed that in one case he should test high 
and in the other case low, compared with the group of ap- 
plicants. Of course, no conclusions can be drawn from 
comparisons of a group with but one or two individuals, and 
this procedure has nothing to commend it except the added 
zest which the management finds in the experiment. 
As an extension of this method Scott proposed comparing 
test scores of a group of proved experts and a group of 
applicants. Those applicants who test the same as the 
experts are then considered favorable material. The un- 
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