of the boys and girls were treated separately there
was found a small but fairly constant superiority of the girls up to the
age of 13 years. At 14, however, the curve for the girls dropped below
that for boys. This is shown in Figure 3.

The supplementary data, including the teachers' estimates of
intelligence on a scale of five, the teachers' judgments in regard to
the quality of the school work, and records showing the age-grade
distribution of the sexes, were all sifted for evidence as to the
genuineness of the apparent superiority of the girls age for age. The
results of all these lines of inquiry support the tests in suggesting
that the superiority of the girls is probably real even up to and
including age 14, the apparent superiority of the boys at this age being
fully accounted for by the more frequent elimination of 14-year-old
girls from the grades by promotion to the high school.[23]

[23] It will be remembered that this series of tests did not follow up
and test those who had been promoted to high school.

2. However, the superiority of girls over boys is so slight (amounting
at most ages to only 2 to 3 points in terms of I Q) that for practical
purposes it would seem negligible. This offers no support to the opinion
expressed by Yerkes and Bridges that "at certain ages serious injustice
will be done individuals by evaluating their scores in the light of
norms which do not take account of sex differences."

3. Apart from the small superiority of girls, the distribution of
intelligence in the two sexes is not different. The supposed wider
variation of boys is not found. Girls do not group themselves about the
median more closely than do boys. The range of I Q including the middle
fifty per cent is approximately the same for the two sexes.[24]

[24] For an extensive summary of other data on the variability of the
sexes see the article by Leta S. Hollingworth, in _The American Journal
of Sociology_ (January, 1914), pp. 510-30. It is shown that the findings
of others support the conclusions set forth above.

4. When the results for the individual tests were examined, it was found
that not many showed very extreme differences as to the per cent of boys
and girls passing. In a few cases, however, the difference was rather
marked.

The boys were decidedly better in arithmetical reasoning, giving
differences between a president and a king, solving the form board,
making change, reversing hands of clock, find