AY
PREDICTION OF VOCATIONAL SUCCESS
Prediction based on group comparison. Critical scores and critical sections.
THE two foregoing chapters dealt with the determination
of the relationship between measurements and the criterion
of vocational accomplishment. When significant relationships
 have been discovered either by inspection or by the
statistical methods there described, the relative value of particular
 scores in forecasting vocational success must be determined
 before practical use can be made of these findings.
Two general types of procedure are available, one based on
the study of group differences, the other on the establishment
 of correlation between measurements.
PREDICTION BASED ON GROUP COMPARISON
The groups to be compared are made up of the successful
and the unsuccessful employees; or those who remain with
the company and those who leave; those who learn quickly
and those who take a longer time to acquire the necessary
vocational skill; those who earn a promotion and those who
do not; those who have few accidents and those who have
many; those who sell more than their quota and those who
sell less, and so forth. When two or more groups representing
 different levels of vocational accomplishment are to be
compared in terms of test scores, practical procedure demands
 a way of determining the score or scores which best
differentiate the group or groups.
A test score above which or below which the members of
one group are represented in conspicuously greater proportion
 than the members of the other group, is called a critical

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