Evaluation of the dimensions of the spherical model of vocational interests in the long and short version of the Personal Globe Inventory

Abstract

The present study examined three different sources of evidence for the validity of the Personal Globe Inventory (PGI; Tracey, 2002) with regard to its ability to assess the dimensions underlying the spherical model of vocational interests: People-Things, Ideas-Data, and Prestige. Specifically, we analyzed 1) evidence based on the internal structure of the eight basic interest scales, 2) convergent evidence of the PGI dimensions across different item types, and 3) evidence based on relations to plausible correlates of vocational interests, namely, gender, academic achievement, and the socioeconomic status associated with the desired profession. Moreover, we analyzed the extent to which these sources of evidence were invariant between the PGI and its associated short version – the PGI-S (Tracey, 2010). Relying on a sample of N = 688 university students in Germany, we were able to show that 1) the circular order of the basic interest scales was confirmed across item types and that it was invariant across PGI versions, 2) both the relationships between corresponding dimensions across item types as well as the relationships with the validity markers were, as far as the circumplex dimensions were concerned, in line with theoretical expectations and invariant across PGI versions, and 3) there were notable differences between the respective relationships with the Prestige dimensions across item types and PGI versions. We conclude by weighing up the pros and cons of the two PGI versions and suggesting specific situations in which the use of either version is advised.