Although there were certain inadequacies in the tests applied, as well as in the judgments obtained from office heads, the value of the results became more and more clear with each passing month. For example, 188 clerks recommended on the basis of the tests and followed up at intervals of one month for a period of three months were estimated as follows: Percentage of those called good by their superiors At the end of one month 75% At the end of two months 89% At the end of three months 92% Another series of interesting experiments to determine the mental capacity of workers in industry was directed at stenographers, typists, and comptometrists. The work of these kinds of workers has been specialized by the use of a standard machine, and in applying tests to this kind of work it was necessary, therefore, to take into consideration two important factors: first, the skill already acquired by the workers at a certain machine; second, the aptitude which the worker possessed for improvement in the use of the machine. Relevant tests were given to two senior classes of more than three hundred girls and boys in a commercial high school, to seventy-six pupils in two business schools, to a group of twenty-two office typists, to another group of nineteen stenographers, to over four hundred candidates for positions as typists and stenographers, to three groups of more than one hundred and forty comptometrists; and finally, to more than one hundred and twenty candidates for comptometry. More than one thousand persons were tested and more than five thousand tests were given. Tests for typists included copying, spelling, substitution, and the Trabue Completion test. In the copying and spelling tests, office forms were used. A number of words, purposely misspelled in characteristic fashion, were mingled with words correctly spelled, and the applicant was asked to check off those incorrectly spelled. It was discovered, in the substitution test, that if an applicant without much previous experience in typing does very well in the test, the indication is that she has the necessary aptitude or potential ability to become a good typist with practice. The success of the applicant in the Trabue Completion test indicated his or her ability to complete sentences parts of which are missing. The ability to do this is a great advantage to the typist and one which will increase her capacity. The Trabue Completion test also proved valuable in determining the ability of stenographers. The most important test probably, for a stenographer, is of her ability to take and transcribe dictation. Tests were given as nearly as possible at the speed which was best adapted to the applicant’s ability. The results were then graded on the basis of the total time consumed and the amount of work done correctly.