EMPLOYMENT PSYCHOLOGY (42) o=V Npq N is the number of cases, p the proportion of these cases giving one answer to the item, and ¢ the proportion giving the other answer. We have described the practical procedure to be followed when the success of the applicant is to be predicted from a measurement. The measurement may be a test score, a questionnaire item, an interview rating, or any one of the facts about an applicant’s personal history which can be quantified and correlated with a criterion of successful accomplishment. In actual practice, probability of success is, of course, usually predicted from a combination of such items. The more information the better, provided its significance is known and not merely guessed at. When predicting success from a number of such measurements it is necessary to combine them in such a way that the resulting total score will have maximum predictive value. This procedure forms the subject of the next chapter. 202 1