Chapter XIII. THE THEORY OF THE MEASUREMENT OF MENTAL DEVELOPMENT 252

A. COMPARISON OF UNITS AND SCALES FOR MEASURING INDIVIDUAL 254 DIFFERENCES

(a) Equivalent Units of Ability When the Distributions 254 are Normal

(b) The Year Unit of the Binet Scale 260

(c) Is Tested Capacity Distributed Normally? 267

(d) Equivalent Units of Development When the Form of 275 Distribution is Uncertain

B. THE CURVES OF MENTAL DEVELOPMENT 279

(a) The Significance of Average Curves of Development 280

(b) Changes in the Rate of Development 290

(c) The Question of Earlier Arrest of Deficient Children 294