Biosocial influences on sex differences, found for school achievement test results in grades 3 and 6, have been studied by means of opposite-sex twin pairs and singleton controls, attending the same classes as the twins. As expected the opposite-sex twin pairs tend to be more similar in achievement test results in Swedish and mathematics than…

A comparison was made of ability and achievement test results and school grades for 323 pairs of Swedish male and female twins and 740 controls in relation to social background. An interaction effect of sex and social background was found for verbal ability and mathematics test results. (SLD)

As part of a continuing evaluation of the Swedish school system, changes in intelligence test scores from 1960 to 1995 were studied in relation to cohort, gender, and socioeconomic background. Changes in verbal, spatial, and reasoning ability were studied by comparing results on identical tests given to representative samples of Swedish…