Personality, Basic Psychological Needs, and Well-Being Across 22 Countries: Simulating Measurement Constraints in a Global Panel Study

Personality–well-being associations are widely documented, yet evidence from longitudinal, cross-national samples remains limited and often relies on ultra-brief measures with uneven psychometric performance. Using longitudinal data from the Global Flourishing Study (GFS; N > 200,000 across 22 countries), we examined whether Big Five traits relate to well-being via half-longitudinal indirect pathways through basic psychological need satisfaction. Personality was assessed with the Ten Item Personality Inventory (TIPI), and well-being outcomes included life satisfaction, life worthwhileness, and happiness. Preregistered two-wave half-longitudinal mediation models, following recommendations for two-wave panel data, tested indirect pathways from conscientiousness, agreeableness, and openness to well-being via competence, relatedness, and autonomy, respectively, controlling for prior levels of the mediator and outcome. Exploratory robustness analyses to evaluate cultural moderation and measurement sensitivity. Country-specific trait–life satisfaction slopes were estimated and meta-regressed on Hofstede’s Individualism–Collectivism index (IDV), with additional reliability-adjusted models incorporating country-level internal consistency estimates and sensitivity analyses using single-item (positively keyed) personality indicators. Across models, basic psychological needs robustly predicted subsequent well-being. In contrast, personality–well-being associations and apparent cultural moderation patterns were highly sensitive to measurement precision, particularly for conscientiousness and neuroticism. Results highlight both the value and inferential limits of ultra-brief personality assessment in global panel studies, highlighting the importance of routinely evaluating reliability variability, item functioning, and robustness when interpreting cross-national personality–well-being effects.