Page:Popular Science Monthly Volume 67.djvu/549

Rh Fidelity of the Reports.—There is no way to know whether the reports are truthful and reliable statements of the students' activities save by the internal evidence of the reports themselves. Judged in this way and in the light of the general interest manifested in the matter at the time, the writer feels confident that a high degree of reliability can be attached to the 895 reports which were admitted to tabulation.

Accuracy of the Reports.—About one third of the reports contained inaccuracies, chiefly errors in the addition of the totals, or, less often, errors in the number of hours recorded per diem—25 being a favorite amount! These errors obviously rendered it impossible to tabulate the reports with any accuracy, so that every one of the 895 reports had to be added anew—an operation requiring some 75 hours of solid work for two persons. Obvious errors were corrected on the spot; many reports were returned to students for revision, but, in a few cases, where this was not feasible, minor errors were corrected by the writer in accordance with his own judgment.

Averages and Variations.—For economy's sake the mean variations have been omitted from the tables which follow, for, although they afford a concise index of the uniformity of the individual instances summarized in the average value, their computation would consume more time than they are worth. In place of the mean variation we have recorded the two extremes of individual variation for each group, as 'high' and 'low,' respectively, while the index of uniformity which would have been supplied by the mean variation is afforded by a comparison of the average values for the same item in different groups and classes. Thus the high uniformity of the time registered for sleep is shown by comparing the final average for sleep, 7.90 hours daily, with the same average in the table by classes (8.00, 7.96, 7.77, 7.83) or in the table of courses (8.00, 7.86, 8.22, 7.75, 7.90, 7.91, 7.62, 7.76, 7.95, 7.74, 8.02). Or, again, the relative uniformity of the results for the various groups and classes can be shown fairly well by computing what might be called the 'mean group-variation,' both in terms of absolute hours and in percentage of the final average. Thus, when we compare the averages found for sleep for freshmen arts, sophomore arts, junior arts, senior arts, first year law, etc., through the 39 primary groups, with the final average for all students taken collectively, we mid (Table 5) a mean variation for these group averages of slightly less than three per cent., while that for meals is eight per cent., and so on.

Explanation of the Tables.—With these apologies and explanations we are ready to examine the results themselves.