Research seminar: The Rise and Fall of Norwegian Ability Scores

Ole Røgeberg :   https://www.frisch.uio.no/medarbeidere/olejr/

Frischsenteret

The Rise and Fall of Norwegian Ability Scores

Abstract:  The average ability scores of Norwegian males on a military conscription test increased over time throughout much of the 20th century. Scores reached a peak with the 1975 birth cohort, and later scores have shown declines. Such positive and retrograde Flynn effects have also been found in other countries, and a large number of hypotheses have been proposed to explain their causes and implications. We show that the positive trend, the turning point and the decline seen across the 1962-1991 birth cohorts can be recovered from within-family variation. As within-family secular trends in average IQ are only predicted by a subset of the proposed theories, this allows us to narrow the set of hypotheses that could plausibly explain the changes in Norway. Using sibling scores we also show that the increasing share of non-tested males across the post-1980 cohorts is selective, and estimates correcting for selection into scoring indicates that the post-1975 decline is larger than the decline in observed scores.