EMPLOYMENT PSYCHOLOGY
of the rater in preparing his master scales. Raters differ
considerably among themselves in judging men by this
method. Some of them tend to ignore the key men entirely
in making their ratings and fall back upon their general
conceptions of excellence in the ability in question. For an
excellent critical analysis of this form of rating scale, see
Rugg (156).
The scale of alternatives or two steps. The judgment is
given in the form of a Yes or No answer to the question:
“Does the man possess this ability?” The difficulty with this
simple method is that most abilities are not distributed in
this all-or-none way. Abilities more often are found to be
distributed among people in general in accordance with the
normal probability curve. In other words, most people have
neither a very small amount nor a very large amount of an
ability. The judge finds himself unable to make satisfactory
 or accurate decisions regarding these people who do not
deviate greatly from the average in this ability.
Per cent scales. The judge rates each man in terms of per
cents much as he would mark an examination paper, on the
assumption: that 100% is the maximum amount of the
ability that any man can possess. This implies a finer discrimination
 than is possible or desirable. Moreover, two
raters can rarely be found who agree on how much 100%
of the ability is, or 80%, or 50%. They really use different
measuring sticks.
Per cent scales sometimes require the judge to estimate
the per cent of the general population which in his opinion
this man would excel in the ability.
Multiple-step scales. The judge indicates his estimate of
the amount of the ability each man possesses by checking
one of a series of symbols. In the following scales, a plus
sign indicates a high degree of the ability in question and
a minus sign a deficiency in the ability. The meaning of the
other symbols is obvious.

126