While considerable support has been obtained for the distinction, due to Cattell and Horn, between the broad factors fluid intelligence (Gf) and crystallized intelligence (Gc), there is also some evidence that Gf is equivalent to the factor of general intelligence (g). This hypothesis is investigated by using LISREL to specify higher-order models in reanalyses of three sets of psychometric data from subjects 11, 13, and 15 years old, respectively. The three studies unanimously showed Gf to be equivalent with a general factor. The discussion is centered upon the use of LISREL and the differences in results between the exploratory and confirmatory approaches to factor analysis.

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A battery of cognitive tests was administered in the 6th grade (12-year-olds) and again in 9th grade (15-year-olds) to a sample of 225 boys and 242 girls. In the 8th grade, the same students answered an inventory about reading activities. Hierarchical confirmatory factor models were fitted to the test data from each of the 2 occasions, defining a General Intelligence factor and residual factors representing Crystallized Intelligence and General Visualization. Results indicate high stability for the general factor (.92 to .94) and for the residual of the General Visualization factor. There were strong autoregressive relations among the latent variables but no or weak cross-lagged relations. Few relations were found between reading activities and changes in abilities. Cattell's investment hypothesis of ability development is discussed in relation to the results.Recent analyses of the dimensional structure of ability tests have suggested a neo-Spearman organization, with a general factor coinciding with Cattell's (1963Cattell's ( ,1971) Fluid Intelligence factor (Gf) and broad residual factors of Verbal-Educational Knowledge (or Crystallized Intelligence, Gc), Visual-Spatial Ability (Gv), Speediness (Gs), and Fluency or Retrieval (Gr)

A simple-structure factor analysis of test data from a sample of 144 fourthgrade children in Norway was carried out. Intellectual tasks related to formal teaching of complex skills formed a rather tight unit at that age and in a school system with little specialization at that level. Second-order factors interpreted to represent Broad Visualization, Speediness, Fluid, and Crystallized intelligence intercorrelated substantially, the correlation between Fluid and Crystallized intelligence being the highest. The results were generally consistent with the predictions from the Cattell-Horn theory of fluid and crystallized intelligence. The results are also discussed in relation to the agedifferentiation hypothesis.

The importance of socio-economic factors and sex differences in an educational system characterized by mainstreaming, no ability grouping within classes, very little acceleration, and no holdbacks of students was studied. Cohort data of 16-year-olds from the township of Trondheim (N = 1750) and a sample of about 250 students were analyzed, using graduate records, questionnaires and inventories. Sex differences in average achievements were small, over-all about 0.4 SD in favour of girls for Norwegian (mother language) and about 0.1 SD in favour of boys for mathematics. However, the proportion of boys who obtained the highest grade in mathematics was larger than expected from the mean difference in the subjects. Parent education was a powerful predictor of student achievement. Questionnaire data showed that sex-stereotypes were strong regarding abilities and career aspirations. The analysis suggested several ways in which sex and socio-economic differences in achievements may be mediated in an egalitarian society.