: EMPLOYMENT PSYCHOLOGY
ability have the same form of distribution as precise measurements
 of that ability in the same group of people, is
insufficient evidence for concluding that ratings and measurements
 are correlated.
With a large number of cases a spotty distribution indicates
 that certain portions of the scale are being neglected
by raters, or that the steps on the scale are not of equal
value. This matter of equalizing the steps on the rating
scale involves considerable labor, and is usually omitted except
 for very refined work (67). If the scores on the rating
scales are transmuted into ranks, nothing is lost by inequalities
 of steps on the rating scale.
Spread of distribution is a fifth basis for comparison of
rating methods. This is an important factor, since sufficient
discrimination between abilities is necessary in order to
compute correlation coefficients and to distinguish between
one man’s ability and another’s. The greater the spread,
however, the greater the gross error of any single rating.
Absence of %alo effect is a sixth criterion. Halo effect is
the tendency for the judge to be influenced in his ratings on
a specific ability by a general attitude toward the person he
is rating. If the judge likes the person, he tends to rate him
high in all favorable abilities; if he dislikes him, he tends to
rate him low in all favorable abilities. Such poor discrimination
 on the part of judges results in high correlations between
 ratings on unrelated abilities. Thorndike reports
correlations of 4.58 between intelligence and leadership,
+ .51 between intelligence and physique, and --.64 between
intelligence and character, when one judge rated 137 aviation
 cadets on the Army Scale (189). He also reports an
average correlation of --.67 between general ability for
officer work and so highly specialized an ability as flying
ability, when the same men were rated by eight judges.
The average rater will not rid himself of this bias and exercise
 his analytical powers unless the scale itself aids him
to do so; consequently the absence of halo may be con-134