EMPLOYMENT PSYCHOLOGY
who are high, average, and low in the ability in question.
Then he takes each group in turn and ranks the men in it.
By assembling his groups of cards in proper order he completes
his ranking.
The order-of-merit method makes distinctions in ability
which are finer than necessary or even possible if the group
is large. It gives the rater no framework on which to hang
his judgments. Moreover, unless statistical corrections are
made, it assumes that a unit difference in rank always indicates
a constant difference in abilities, whereas this difference
is greater at the extremes of ability than in the middle
range. If 50 men are ranked in any ability, the difference
in ability between the first and second man is greater than
the difference between the twenty-fourth and twenty-fifth
man. In spite of these disadvantages the order-of-merit
method is one of the best known, since it gets at the heart
of the matter by disregarding all other persons or impressions
and simply requiring comparisons between the members
of the group under consideration.
Grouping. The judge places the subjects in three groups,
consisting of those who excel in the ability, those who are
undistinguished in the ability, and those who fall below
in the ability. The judge may or may not be instructed to
make the groups equal in size. The number of groups may
be increased at the discretion of the investigator. Symonds
contends that seven is the optimum number of groups,
although he has not proved his point experimentally (179).
Ratings of several judges may easily be combined if a numerical
value is assigned to each of the groups.
The Scott form of man-to-man comparison scale. This
is the rating method originally developed at Carnegie Institute
of Technology for the selection of salesmen, and later
adapted for use in rating officers in the United States Army
during the World War (137). The judge makes a master
scale for each ability by the following process: He selects
the highest and the lowest man in the ability in the group
124A
