Improving the Big Five Inventory-2 in an Italian context using Rasch Analysis (BFI-2-R)

The Big Five Inventory-2 (BFI-2) is one of the most used questionnaires to assess personality traits. Its main strength regards the possibility of distinguishing the five traits into 15 facets. Despite its extended usage and validation, there is still room for research to explore its structure and potential. For instance, an examination of the facets through Rasch Analysis (RA) has not been developed yet. We investigated the psychometric properties of the BFI-2 by applying the RA (obtaining the BFI-2-R), in addition to traditional analyses, in an Italian sample of 5362 adults. First, we conducted five confirmatory factor analyses, which supported the three-facet structure of each of the five traits. This structure resulted invariant at the scalar level across sex. Second, for each facet we checked and confirmed the necessary assumptions for applying the RA (i.e., about monotonicity, local independence, unidimensionality, and differential item functioning). We then found that our data fit the Rasch model for each facet. Finally, based on the Rasch scores, we documented the discriminant and convergent validity of the BFI-2-R. Overall, the findings support the goodness of the BFI-2-R and permit to extend research on the Big Five with an instrument considering the properties of fundamental measurement.