A reliable instrument for making use of an overly neglected source of information on personality: The French adaptation of the Big Five Inventory-2 (Bfi-2) informant-report form.

Objectives: The assessment of personality traits is most often based on self-report. However, a growing body of research has shown that informant-report is a valuable and too often overlooked source of unique information. The aim of this study was to validate the French version of the informant-report form of the Big Five Inventory-2 (BFI-2) which assesses 15 facet traits in addition to the five major trait domains.

Methods: We asked 699 psychology and sports science and technology students to describe a person they knew well using the BFI-2 and obtained 661 valid records with demographic information. The data were analyzed using a bi-factor exploratory structural equation model with five bifactors corresponding to the Big Five domains, and three group factors (facets) each.

Results: This model had an excellent overall fit. Cronbach's alpha coefficients for the five domains were very satisfactory and the McDonald's omega coefficients were even better. The scales that measured the five major factors were therefore highly reliable, although Extraversion was somewhat less so. The scales measuring facets all had high reliability as measures of the whole formed by the major factor and the group factor. In addition, ten of them were reliable measures of their specific factor, and the remaining five appeared to be pure measures of the five domains.

Conclusions: The informant-report form of the BFI-2 is a reliable instrument which is easy and quick to administer. These qualities should enable clinicians and researchers to exploit the much-neglected source of original information provided by informant-reports.