Measurement invariance of the Five-Factor Obsessive-Compulsive Inventory in a U.S. census-matched sample: Demographic differences in obsessive-compulsive personality disorder traits across age, gender, and education.

The Five-Factor Obsessive-Compulsive Inventory (FFOCI) provides an assessment of personality traits relevant to obsessive-compulsive personality disorder. Obsessive-compulsive personality disorder is the most prevalent personality disorder within community samples, and the literature marks that some demographic groups are more at risk than others. The FFOCI, however, has never been explored to demonstrate that it assesses these traits in the same way across groups. The current study adds to the literature by evaluating its measurement invariance across gender, education, and age via the alignment method in a sample of 500 U.S. census-matched adults. A novel contribution of the study is the use of the alignment method, which suggested that the FFOCI demonstrated invariance across groups, allowing for mean-level comparison in traits related to overcontrol. Analyses demonstrated that invariance of the FFOCI held across age, gender, and educational level. Mean-level comparisons between groups showed that college-educated individuals were not significantly higher than noncollege-educated on traits relating to overcontrol. There were nuanced differences between men and women, and differences between age groups were more complicated than originally anticipated. (PsycInfo Database Record (c) 2026 APA, all rights reserved).