Psychometric properties of the Psy-flex scale: A validation study in a community sample in Korea

This study examined the psychometric properties of the recently developed six-item Psy-Flex among community samples in Korea. Using a cross-sectional design, data were collected from 1059 participants. Three bilingual experts translated the scale to ensure content validity. Factor analysis was employed to confirm the factor structure, and a polytomous item response theory model was used to examine the individual items and entire scale. The theory-based single-factor structure was confirmed using a Korean community sample, and measurement invariances were found across sex and age groups. In addition, the scale showed a moderate relationship with established measures of interest. Furthermore, item and categorical functioning were investigated using the polytomous Item Response Theory (IRT) model (i.e., the Generalized Partial Credit Model [GPCM]), identifying well-functioning (e.g., items 4, 5, and 6) and suboptimal (e.g., item 2) items. Additionally, the results suggest that the participants might not be able to meaningfully differentiate the original five-response categories. To the best of our knowledge, this is the first attempt to validate the Psy-Flex in Korea. We believe that the findings are of considerable value in facilitating our understanding of the scale and, more broadly, the construct of psychological flexibility.