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 Childs and

Terman in 1910-11, and of 300 children by Trost, Waddle, and Terman in

1911-12. For various reasons, however, the results of these tests did

not furnish satisfactory data for a thoroughgoing revision of the scale.

Accordingly a new investigation was undertaken, somewhat more extensive

than the others, and more carefully planned. Its main features may be

described as follows:--



1. The first step was to assemble as nearly as possible all the results

which had been secured for each test of the scale by all the workers of

all countries. The result was a large sheet of tabulated data for each

individual test, including percentages passing the test at various ages,

conditions under which the results were secured, method of procedure,

etc. After a comparative study of these data, and in the light of

results we had ourselves secured, a provisional arrangement of the tests

was prepared for try-out.



2. In addition to the tests of the original Binet scale, 40 additional

tests were included for try-out. This, it was expected, would make

possible the elimination of some of the least satisfactory tests, and at

the same time permit the addition of enough new ones to give at least

six tests, instead of five, for each age group.



3. A plan was then devised for securing subjects who should be as nearly

as possible representative of the several ages. The method was to select

a school in a community of average social status, a school attended by

all or practically all the children in the district where it was

located. In order to get clear pictures of age differences the tests

were confined to children who were within two months of a birthday. To

avoid accidental selection, _all_ the children within two months of a

birthday were tested, in whatever grade enrolled. Tests of foreign-born

children, however, were eliminated in the treatment of results. There

remained tests of approximately 1000 children, of whom 905 were between

5 and 14 years of age.



4. The children's responses were, for the most part, recorded

_verbatim_. This made it possible to re-score the records according

to any desired standard, and thus to fit a test more perfectly to the

age level assigned it.



5. Much attention was given to securing uniformity of procedure. A

half-year was devoted to training the examiners and another half-year to

the supervision of the testing. In the further interests of uniformity

all the records were scored by one person (the writer).