Any definite factors available for the school that have a prognostic value in reference to school failures will help to perform a function quite comparable to the science of preventive medicine in its field, and in contrast with the older art of doctoring the malady after it has been permitted to develop. Such prognostication of failure, however, need not imply a complete knowledge of the causes of the failures. It may simply signify that in certain situations the causes are less active or are partly overcome by other factors. Perhaps one of the simplest factors with a prognostic value on failure may be found in the facts of attendance. Persistent or repeated absence from school may reach a point where it tends to affect the number of failures. It happened, unfortunately, that the reports for attendance were incomplete or lacking in a considerable portion of the records employed in this study. Consequently the influence of attendance is given no especial consideration in these pages, except as explained in Chapter I, that the pupil must have been present enough of any semester to secure his subject grades, else no failure is counted and no time is charged to his period in school. In this connection, Dr. C.H. Keyes[14] found in a study of elementary school pupils that of 1,649 pupils losing four weeks or more in a single year 459 belonged to the accelerate pupils, 647 to those arrested, and 543 to pupils normal in their school work. He accredits such large loss of time as almost invariably the result of illness and of contagious disease. He also says, "Prolonged absence from school is appreciable in producing arrest especially when it amounts to more than 25 days in one school year." But the diseases of childhood, with the resultant absence, are less prevalent in the high school years than earlier. Furthermore, the losses due to change of residence will not be met with here, for, as explained in Chapter I, no transferred pupils are included subsequent to the time of the transference either to or from the school.