In age, on the other hand, there was a preferred range. Girls nineteen years of age or younger at date of hiring were a little more likely to be successful than those twenty years old or older. The difference was not great. About 50 per cent of the younger ones succeeded and about 34 per cent of the older ones.

As to schooling, the data did not give clear-cut results. Few candidates with high-school training had been hired. Many had not even completed grammar school; indeed, the preference was slightly in favor of those who had not finished the grammar grades.

As to average length of time on previous jobs, we tried various ranges and finally found this preferred range: if the average was less than one year, it was an unfavorable indication; if it was one year or more, the indication was favorable.

So we went through all the items available. Most of the findings simply confirmed impressions that the employment interviewers already had in mind, although they may not have been giving as much weight to some of the items as they did after their actual statistical significance had been determined.

As to nationality, however, some interesting results appeared which had been anticipated only in part. Using the data on the application blank, we classified the employees in five groups according to racial stock. In the first group were the Austrians, Germans, and Scandinavians. Of these, 63 per cent were successful. Then came the Czechoslovak and Polish, the largest group, of whom 50 per cent were successful on the job. Of the Italians, 43 per cent were successful. Then the Irish, English, and Scotch, that is, the foreign English-speaking stocks, of whom 26 per cent were successful. Of the Americans (defining Americans for this purpose as those whose fathers were born in this country) only 19 per cent were successful in this occupation.

These differences are striking. Instantly there occur many possible explanations, social and educational, as to why American girls in that community prefer to take lower wages working as clerks, than to earn better wages at such factory work as this. Whatever the reasons, here is an instance in which the statistical method applied to familiar data from the application interview, revealed information significant for predicting likelihood of success, thus supplementing the ordinary procedures of hiring and placement. Such aids can be employed only when there is a sufficiently large number of employees in a single occupation, and when reliable, clean-cut criteria of success in that occupation are available. Probability tables based on data of this sort have been compiled from their own extensive experience by several firms maintaining large sales organizations and by groups of life insurance companies whose expenditures in recruiting and training successful salesmen of life insurance constitute a measurable item of expense to the purchaser.

It is not only data of the kind described which lend themselves to useful purposes when gathered carefully and subjected to quantitative evaluation. The interest questionnaire or occupational preference blank also is used in this way.

Somewhat similar approaches to quantitative determination of professional aptitudes are those which resort to the free association experiment and similar sources for data regarding temperament, tastes, and emotional attitudes. In this field of inquiry, Kenagy and Yoakum, Freyd, Wells, Laird, and O'Connor may be mentioned as among those who have not neglected the application of these techniques to industrial situations. Behavior data, which may be gathered quite incidentally to the administering of tests of intelligence or skill, are another source of information regarding significant differences of temperament and attitude. Finally, the personal interview, skillfully administered, may be made to yield suitable grist for the statistical mill.

The employment psychologist or the vocational counselor has done but part of his task when he has developed and applied suitable measures of ability to do or to learn to do the particular work in question. He needs also reliable techniques to aid in predicting probable contentment and satisfaction in that work. We have seen that predictions may in many instances be based on statistical evaluation of data already at hand, but too often neglected, or used only in an intuitive or common-sense way. Such data are found on application forms, physical examination records, and preference questionnaires. They may be gleaned as by-products of the personal interview or of intelligence and trade test performance. They should be used with discretion, after their reliability and their validity for the particular purpose have been statistically determined.

Psychological Aspects of Safety. Ours is a dangerous age. The tempo of modern living has been accelerated far beyond anything imagined by our fathers. The pace of traffic, by land, sea, and air, matches the increasing speed of factory machines. The resulting hazards have challenged the ingenuity of engineers, who have invented clever protective devices, guards, and automatic controls. But in spite of the perfection of these mechanical aids to safety, serious accidents have continued to occur in great numbers; for failure of the human factor causes far more mishaps and disasters than failure of a mechanism. And so industrial psychology has sought, with gratifying success, to make its contribution to safety.

"The best safety device," my friend Bill Pfouts used to say, "is located above the neck." What has industrial psychology done to improve the efficient operation of this device?

The story would be long, if all were told. Distinguished psychologists in Germany, Russia, France, Denmark, Italy, and other lands have delved into the mysteries of motive and habit, attention and distraction, visual acuity, reaction time, susceptibility to fatigue, self-control, and other aspects of human nature, in search of obscure causes of proneness to accidents and ways of eradicating them. Our colleagues of the British Industrial Health Research Board have studied large numbers of apprentices and employees in shipyards and factories, to determine the relation of accidents to monotony of work, to proficiency, and to various differences of ability and personality. Their statistical investigations early proved that industrial accidents do not just happen; they are not distributed among the workers according to the laws of chance. In this country also, in studying records of accidents among factory employees, street-car motormen, automobilists and bus drivers, more than half the accidents have been found to occur to a relatively small proportion of the men. These accident-prone workers are, for the most part, as eager to avoid accidents as any of the others. They have had the same training and supervision. They see the same posters and take part in the same safety drives. So the problem of the industrial psychologist is clearly that of developing the most effective ways of studying these accident-prone individuals and helping them to overcome their particular proclivities.