The internal and external validity of the latent vocational interest circumplex: Structure, relationships with self-concepts, and robustness against item-order effects

The vocational interest circumplex implies a pattern of correlations that can be represented by the interest domains’ locations on the circumference of a circle. In addition, the circumplex can be extended by placing external covariates into the two-dimensional interest structure. Results that simultaneously support the circumplex as a model for the interest scales’ internal structure and for their external relationships with covariates provide a more comprehensive account of the circumplex’s validity than isolated analyses of just one kind of validity evidence. In this article, we outline a latent variable framework that makes it possible to simultaneously examine both validity aspects and that enables researchers to study the robustness of such validity evidence across groups. We applied this framework to the eight basic interest scales of the Personal Globe Inventory (PGI; Tracey, 2002) and their relationships with nine measures of domain-specific self-concepts. Participants were randomly assigned to groups in which the interest items were presented in different orders with the goal of eliciting either cross-domain or within-domain comparisons. Our results suggest that the circumplex structure was remarkably similar (although not fully invariant) across conditions and that the relationships between the PGI scales and the self-concept domains were in good agreement with the circumplex regardless of item order. Interestingly, most self-concept scales occupied positions along the People-Things axis of the circumplex, thereby replicating previous results on the relationships of vocational interests and ability-related constructs. Taken together, our results provide strong support for the internal and external validity of the interest circumplex as an integrative map for representing complex construct relationships.