ORIGINAL RESEARCH article
Front. Psychol.
Sec. Quantitative Psychology and Measurement
Validating the Korean Version of the Flourish Index and the Secure Flourish Index: Integrating Classical Test Theory and Item Response Theory
Jaeyoung Ha 1
Dorota Weziak-Bialowolska 2
Yoon Young Choi 1
Soong-nang Jang 3
Jieun Hwang 4,5
Sung-il Cho 6,7
1. Seoul National University Graduate School of Public Health, Gwanak-gu, Republic of Korea
2. Akademia Leona Kozminskiego, Warsaw, Poland
3. Chung Ang University Red Cross College of Nursing, Dongjak-gu, Republic of Korea
4. Dankook University Department of Health Administration, Cheonan-si, Republic of Korea
5. Dankook University College of Public Health Sciences, Cheonan-si, Republic of Korea
6. Graduate School of Public Health, Seoul National University, Seoul, Republic of Korea
7. Seoul National University Institute of Health and Environment, Seoul, Republic of Korea
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Abstract
This study validated the Korean versions of the Flourish Index (FI) and the Secure Flourish Index (SFI), providing psychometric evidence and culturally grounded insights into the multidimensional construct of flourishing. Human flourishing is conceptualized as a state of complete well-being encompassing five core domains: (D1) happiness and life satisfaction, (D2) physical and mental health, (D3) meaning and purpose, (D4) character and virtue, and (D5) close social relationships, and one sustaining domain, (D6) financial and material stability. In total, 1,217 adults participated in an online survey conducted between January 30 and February 8, 2024. To ensure comprehensive validation, scale-level reliability and structural validity were examined using classical test theory, while item-level functioning was evaluated using unidimensional and multidimensional graded response models within an item response theory framework. The findings supported the conceptual and structural validity of both indices while indicating multidimensionality. Specifically, three domains (happiness and life satisfaction, mental health, and meaning and purpose) clustered closely and primarily contributed to the general flourishing factor. In contrast, character and virtue and close social relationships formed a distinct cluster, implying a potential personal–relational distinction. Items in the character and virtue domain showed signs of social desirability bias, while redundancy was noted between items in the close social relationships domain. Measurement invariance was supported at the configural and metric levels, and partially at the scalar level, and no significant differential item functioning was detected. These findings imply that culturally sensitive adaptations may enhance the interpretability and applicability of the instruments in cross-national research, thereby contributing to a more nuanced understanding of flourishing across diverse cultural contexts.
Summary
Keywords
Humans, human flourishing, item response theory, population health, Psychometrics, Surveys and questionnaires
Received
28 August 2025
Accepted
23 January 2026
Copyright
© 2026 Ha, Weziak-Bialowolska, Choi, Jang, Hwang and Cho. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
*Correspondence: Sung-il Cho
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