The Dimensional and Axial Structure of the BigFive Plus Inventory

Cristian Dan Opariuc, Ticu Constantin


This study reports on the adaptation of a personality inventory for the item response models by investigating its structure in order to identify unidimensionality and local independence. We started with the classical form of the BigFive Plus Inventory (Constantin T. , et al., 2008) and we used different techniques to refine the instrument and to identify the structure of the latent traits. First, we analyzed the distribution of observed data within each latent trait. Second, we performed a complete analysis of internal consistency to identify the items-scale relationships and the opportunity to perform a principal component analysis. Third, we performed a principal component analysis using categorical data (CATPCA), and based on centroids and vector coordinates we identified the structure of latent factors. 4647 participants from different socio-economic backgrounds, including students, corporate employees and employees of military structures took part in the study. The results revealed the dimensional structure of BigFive Plus Inventory and the procedures that need to be applied to achieve unidimensionality.

dimensional structure assessment, CATPCA, internal consistency, personality, psychological tests

Cristian Dan Opariuc – “Ovidius” University, Constanța, Romania E-mail:
Ticu Constantin – Al. I. Cuza University, Iaşi, Romania, Faculty of Psychology and Educational Sciences, E-mail:

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