Japanese adaptation of short and extra-short forms of the Big Five Inventory-2

The present study aimed to adapt the Japanese versions of the short and extra-short forms of the Big Five Inventory-2 (BFI-2-S-J and BFI-2-XS-J). In Survey 1, we examined the usability of the 30-item (BFI-2-S-J) and 15-item (BFI-2-XS-J) inventories by comparing them with the original 60-item inventory. In Survey 2, we conducted a survey using the BFI-2-S-J. A total of 962 (Survey 1) and 560 (Survey 2) Japanese adults responded to online questionnaires. Both surveys measured other psychological scales to examine the validity. A random intercept exploratory factor analysis was employed to identify the factor structure. An analysis using item response theory demonstrated measurement accuracy. Convergent and discriminant validity were also confirmed. Additionally, the analyses indicated measurement invariance across demographic groups and the availability of facet-level scores of the BFI-2-S-J within each Big Five domain. Overall, the results indicated that the BFI-2-S-J and BFI-2-XS-J are useful tools for measuring the Big Five personality traits in Japanese samples.