Methods of Calculating Ages Including a Newly Devised Slide Rule
June F. Constantine · The Journal of Educational Research · 1932
In practically all schools record cards are kept for each child ; group tests of achievement and intelligence are administered, and age-grade distributions made. All of these activities require the laborious task of computing ages either by the age-old processes of arithmetic or by the use of some short-cut device. The growth of educational research bu reaus in the past ten years and the resulting increase in the use of edu cational measurements has been phenomenal. The questions which face the school or research worker are : (1) How old were the members of this group on a certain date? (2) When will this person attain a given age? The slide rule to be discussed was con structed to solve either of these problems with the following criteria in mind. An adequate device for computing ages should satisfy the fol lowing criteria: (1) it should be rapid; (2) it should be accurate; (3) it should give the ages to whatever degree of accuracy required ; and (4) it should answer either of the above questions with equal ease. Since the research worker generally uses a thirty day month, it is possible to use equal divisions on all the scales. In order to simplify the matter further a table of yearly increments was devised. A section of this table (Table I) is given below: