The Applications and Mechanical Calculation of Correlation Coefficients in Journal of the Franklin Institute, Vol. 201, No. 3, 1926, pp 337-350

FIRST EDITION DODD'S 1926 CORRELATION COEFFICIENT CALCULATOR. The paper is accompanied by three illustrations and a photograph of his correlation machine. Stuart Dodd, a researcher at Princeton University, built a machine to automatically calculate correlations - a correlation calculator. Correlation is a statistical concept used in many scientific fields and in which two or more quantities are correlated if there is a "connection" between the pairwise values they assume. Dodd's machine performed calculations automatically - and in 1926. "Around 1925 Stuart C. Dodd, a psychologist at Princeton University, made a simpler correlation calculator. This machine contained drums on which square numbers where represented by pins of different lengths (separate pins for units and tens). These drums are the square number equivalent of the multiplication bodies as used in the Millionaire calculator. Dodd designed different versions of this device. Later development was continued by the Cambridge Instrument Co. Inc., New York, who sold these correlation machines to the universities of Harvard, Berkeley, and Chicago" (Correlation Machines, "The contribution of psychologists to mechanical computing," Calculating History web portal). Dodd first presented this work as a lecture of the same title delivered during a meeting at Princeton in January of 1926; the paper offered here is the first and only printed version of that lecture. In it, Dodd "demonstrated a mechanical calculator designed by him and used especially in the calculation of intelligence coefficients. With this machine, Mr. Dodd [made] five statistical calculations with the turn of the handle" (Yearbook of The Franklin Institute, 1927, 80). Later versions of Dodd's machine were known as Dodd Correlators. ALSO INCLUDED: Science and the Earthquake Peril by Ernest Lester Jones, pp. 563-596. CONDITION & DETAILS: Philadelphia: The Franklin Institute. 8vo. (9 x 6 inches). [6], 826, [contents pages of several issues in rear as well as the wraps of the June 1926 issue], 3. Solidly bound in maroon library cloth with minor scuffing at the edge tips. Ex-libris with a pictorial plate of The John Crerar Library of Chicago on the front pastedown, spine call number and a discreet blind stamp on the title page; no other markings. The volume is illustrated throughout. Clean.…