RELATIVE CHANGES IN INTELLIGENCE FROM 13 TO 18: I. Background and methodology

H ärnqvist , K. Relative changes in intelligence from 13 to 18. I. Background and methodology. Scand. J. Psychol ., 1968, 9, 50–64.—A ten-percent sample of the Swedish school population born in 1948 took an intelligence test at the age of 13. The male part was tested again at 18 in connection with enrolment for military service in 1966. Complete test scores are available for 4616 men. The data were used to investigate relative changes in intelligence connected with differences in education and home background. In this report the theoretical and statistical bases for such comparisons are analyzed. In part II the results are reported.