If the separate classes be now considered the results are seen to be more or less irregular, although the general tendency is apparent. If the average results from all six classes are considered the results are more reliable as well as more uniform. The average salary varies in the same way as do the grades. If the average salary of the men of the first quartile ($1,664) be taken as a basis of comparison and considered one hundred per cent, then the salaries of the men in the second, third and fourth quartiles are respectively only eighty-seven, eighty-five and seventy-six per cent of this amount. In general terms, the salary of the men in the lower or poorest quarter of the class, from the point of view of school grades, will be only three-fourths the salary of the men in the upper or best quarter. The two middle quartiles will differ but little from each other, although the second has the advantage, by two per cent, or $44, over the third quarter.
If the class be divided into a better and a poorer half, then the average salary of the men in the upper half is seen to be $1,563, while that of the men in the lower half is only $1,348. The men in the upper half earn $215 more in a year than the men in the lower half. This way of expressing the results is both clearer and more concrete than the mere statement of the coefficient of correlation.
Interesting data on all three of these preceding questions are to be found in A. Lawrence Lowell's study of the academic careers of students in Harvard College, Law School and Medical School. This investigation included an examination into the college entrance examinations, the records attained during the college course, the subjects elected in this course, and the subsequent achievement of the men in the professional schools of law and medicine. The statistics cover the cases of all men who took the degree of A. B. at Harvard and then graduated from the two professional schools connected with Harvard. Only men who had taken at least three years of college work in residence were included. The records for the Law School cover the twenty years from 1891 to 1910. Those for the Medical School cover the sixteen years from 1895 forward.