A Second-Order Longitudinal Model Of Ability Structure

Olsson and Bergman (1977) presented a structural equation model for the development of intellectual abilities between the ages of 10 and 13. Their model proposed four correlated factors, each of which was stable over time. They also found that development on each factor was a function of that factor alone, independent of the other factors. The present paper describes a reanalysis of these data, under a structural model which assumed that a second-order general-intelligence factor (G) could account for the correlations among factors. It was found that, for the sample used, only G and the verbal and spatial ability factors were stable over time. It was concluded that much of the stability found by Olsson and Bergman could be accounted for by the stability of G, and that development on each primary factor was heavily dependent on development of G.