VIII STENOGRAPHERS, TYPISTS, AND COMPTOM- ETRISTS The work of typists, dictaphone clerks, stenographers, and computing-machine operators, is clerical work which is specialized by the use of a standard machine. In apply ing tests to this kind of work, therefore, it is necessary to take into consideration two additional factors: first, the skill already acquired by the worker at a certain machine; and secondly, the aptitude which the worker possesses for learning and improvement in the use of the machine. A typist, for instance, must usually possess, at the outset, a certain degree of clerical ability. However, this is only the foundation of her work. She must also be trained in the use of the typewriter, and she should have, in addition, that aptitude or innate ability which will make her, in time, a fast and accurate typist. The same holds true of other office-machine operators, except that the stenog rapher must also have ability in taking dictation and in reading her notes. In order to find tests which could meet these conditions, an extensive series of experiments was conducted in which relevant tests were given to two senior classes of over three hundred girls and boys in a commercial high school, to seventy-six pupils of two business schools, to a group of twenty-two office typists, to another group of nineteen stenographers, to over four hundred candidates for posi tions as typists and stenographers, to three groups of over 88