Validity Evidence for the K-ULS-8: A Brief Korean UCLA-Based Loneliness Measure for University Student Stress-Related Mental Health Research

Background: Loneliness is relevant to stress-related psychological distress in young adults, but brief Korean UCLA-based measures require item-level validation. Methods: Two independent Korean university student samples were analyzed. Study 1 (n=341 women) used exploratory factor analysis and Rasch rating scale modeling to derive a brief form from Kim’s 20-item Korean Revised UCLA Loneliness Scale adaptation. Study 2 (n=214) examined Rasch cross-validation, gender-related differential item functioning (DIF), and correlations with depressive symptoms and intrusive rumination. Results: The final K-ULS-8 showed acceptable item fit in Study 1 (infit=.81~1.16, outfit=.74~1.14) and Study 2 (infit=.75~1.30, outfit=.72~1.18). Rating-scale thresholds were ordered, and the Rasch dimension explained 56.6% and 54.5% of raw variance in Studies 1 and 2, respectively. K-ULS-8 scores correlated strongly with the 20-item parent scale (r=.918) and positively with depressive symptoms (r=.639) and intrusive rumination (r=.345). Gender-related DIF evidence was preliminary: LON2 showed a potentially meaningful DIF signal, and LON11 showed cross-sample item-location instability but negligible gender DIF within Study 2.Conclusions: The K-ULS-8 provides initial, sample-bound validity evidence as a low-burden measure of affective loneliness for Korean university student mental health and stress-related psychological distress research.