He certainly leaves the impression that it is "mental
ability as we ordinarily think of it" that is re-
sponsible for this association between average IQ
scores and job prestige. But the association can
be interpreted as meaning, just as reasonably, that
it takes more -pull, more opportunity, to get the
vocabulary and other habits required by those in
power from incumbents of high-status positions.
Careful studies that try to separate the credential
factor from the ability factor in job success have
been very few in number.
Ghiselli (1966) simply did not deal with the
problem of what the criteria of job proficiency may
mean for validating the tests. For example, he re-
ported a correlation of .27 between intelligence test
scores and proficiency as a policeman or a detective
(p. 83), with no attention given to the very im-
portant issues involved in how a policeman's per-
formance is to be evaluated. Will supervisors' rat-
ings do? If so, it discriminates against black
policemen (Baehr, Furcon, & Froemel, 1968) be-
cause white supervisors regard them as inferior.
And what about the public? Shouldn't their opin-
ion as to how they are served by the police be part
of the criterion? The most recent careful review
(Kent & Eisenberg, 1972) of the evidence relating
ability test scores to police performance concluded
that there is no stable, significant relationship.
Here is concrete evidence that one must view with
considerable skepticism the assumed relation of in-
telligence test scores to success on the job.