entary information regarding the subject's personal
history, including medical record, accidents, play habits, industrial
efficiency, social and moral traits, school success, home environment,
etc. Without question, however, the improved Binet tests will contribute
more than all other data combined to the end of enabling us to forecast
a child's possibilities of future improvement, and this is the
information which will aid most in the proper direction of his
education.

CHAPTER IV

NATURE OF THE STANFORD REVISION AND EXTENSION

Although the Binet scale quickly demonstrated its value as an instrument
for the classification of mentally-retarded and otherwise exceptional
children, it had, nevertheless, several imperfections which greatly
limited its usefulness. There was a dearth of tests at the higher mental
levels, the procedure was so inadequately defined that needless
disagreement came about in the interpretation of data, and so many of
the tests were misplaced as to make the results of an examination more
or less misleading, particularly in the case of very young subjects and
those near the adult level. It was for the purpose of correcting
these and certain other faults that the Stanford investigation was
planned.[15]

[15] The writer wishes to acknowledge his very great indebtedness to
Miss Grace Lyman, Dr. George Ordahl, Dr. Louise Ellison Ordahl, Miss
Neva Galbreath, Mr. Wilford Talbert, Dr. J. Harold Williams, Mr. Herbert
E. Knollin, and Miss Irene Cuneo for their cooeperation in making the
tests on which the Stanford revision is chiefly based. Without their
loyal assistance the investigation could not have been carried through.

Grateful acknowledgment is also made to the many public school teachers
and principals for their generous and invaluable cooeperation in
furnishing subjects for the tests, and in supplying, sometimes at
considerable cost of labor, the supplementary information which was
called for regarding the pupils tested. Their contribution was made in
the interest of educational science, and without expectation of personal
benefits of any kind. Their professional spirit cannot be too highly
commended.

SOURCES OF DATA. Our revision is the result of several years of work,
and involved the examination of approximately 2300 subjects, including
1700 normal children, 200 defective and superior children, and more than
400 adults.

Tests of 400 of the 1700 normal children had been made by