Validation of the 15-item Things You Do Questionnaire among South Asian adults: a psychometric analysis

Background The Things You Do Questionnaire–15 item version (TYDQ‑15) is a brief self‑report measure assessing adaptive daily behaviours associated with mental health across five behavioural domains. Although the TYDQ‑15 has demonstrated strong psychometric properties in Western populations, its validity among South Asian adults remains largely unexplored. This study aimed to evaluate the factor structure, reliability, and validity of the TYDQ‑15 among South Asian adults. Methods A cross-sectional online survey was conducted among 765 adults from India, Pakistan, and Nepal. Participants completed the TYDQ-15 and the physical and psychological domains of the brief version of the World Health Organization Quality-of-Life Scale (WHOQOL-BREF). Internal consistency was assessed using Cronbach’s alpha, whereas construct validity was examined through confirmatory factor analysis (CFA). Convergent, discriminant, and criterion validity were evaluated using average variance extracted and composite reliability, heterotrait–monotrait ratio, and Pearson correlation with WHOQOL-BREF domains, respectively. Results The TYDQ-15 demonstrated excellent internal consistency overall (Cronbach’s α = 0.91) and across ethnic groups. CFA supported the original five-factor structure, with acceptable to excellent model fit indices across samples (CFI = 0.94–0.98; RMSEA = 0.04–0.07). Convergent and discriminant validity were generally supported, with minor variations by ethnicity. Criterion validity was evidenced by moderate positive correlations with psychological ( r = 0.41) and physical ( r = 0.39) quality-of-life domains (both p < 0.001). Conclusion The TYDQ-15 showed promising psychometric properties among South Asian adults from India, Pakistan, and Nepal, although further research is needed to confirm measurement invariance and cross-cultural comparability.