Chapter III. THE PERCENTAGE DEFINITION OF INTELLECTUAL DEFICIENCY 20

A. THE DEFINITION 20

B. THE ASSUMPTIONS OF A QUANTITATIVE DEFINITION 21

(a) Deficiency is a Difference in Degree not in Kind 21

(b) As to the Variation in the Frequency of Deficiency at 23 Different Ages

(c) As to the Number of Deficients not Detected by Tests 34

(d) Allowance May be Made for Variability 40