Factor retention in the intra-individual approach: Proposition of a triangulation strategy

The intra-individual approach has been proposed by researchers as an alternative to traditional techniques focused on the population level. The central argument is that the inter-individual procedures are appropriate to estimate the population variance but cannot be extrapolated to the individual level. Evidence shows that the factorial structure of intelligence and personality psychometric models usually verified in the population (e.g. Carrol’s three strata factor structure and the Big Five Personality model) are not necessarily found at the individual level. However, the factor analysis in the intra-individual approach has an additional challenge in comparison to the traditional factor analysis: until the present moment there are no fit indices available to the intra-individual factor techniques. The current paper proposes the use of a set of approaches to find the adequate factor retention as a triangulation of data. The proposition will be applied in the psychometric intelligence field