PREFACEThis volume represents the fruits of three years of inve8tigation(from .Tllly 1, 1922, to ,July I, 1925) by the Division of Psychologyof the Institute of Educational Research. It Attempt.s to ans'werthe essential questions conc(!rDin~ the natu're and mel:lning of themeasurement (if a mental fad in the saw pie ca~e of intelligence, orrather of a defined segment thereof. Its conclusions, in so faras they are 'W'arranted, should become the basis of sound practicein the construction and calibration of s(~ales for use in mentl:ll meaml'ement.According to them, the present theory and practice ofmeasurement of mental abilities are justHied to a remarkable degreein certain respects, but in others should be almost recreated.Some of the most important of these conclusions were reachedonly in the last si"" months of the inquiry and l:I.re (~onsequentlypresented 'vitt. less adequate evidential suppor: than is desirable.The concept of area of intellectTable of Contents CONTENTS; elI AP'l'ER L-'1'Ju Present S latus PAGE; Ambigui ty in con tent _ _ _ _ 1; Arbitrarirl:!ss of uuits _ _ 3; Ambiguity in siglliflcaucc 7; ~rl;l)l!;UrOItlc!lt!-; of intelligence are menSlre!; of int
