Can life satisfaction be measured fairly for different groups of South African first-year university students? Testing differential item functioning and invariance of The Satisfaction With Life Scale

Abstract

Student well-being has gradually become a topic of interest in higher education, and the accurate, valid, and reliable measure of well-being constructs is crucial in the South African context. This study examined item bias and configural, metric and scalar invariance of the Satisfaction With Life Scale (SWLS) for South African first-year university students. A cross-sectional design was used. A sample of 780 first-year South African university students was included. Confirmatory factor analysis, differential item functioning (DIF) measurement invariance, and internal consistency were tested. A one-factor structure was confirmed. Item 1 of the SWLS was particularly problematic concerning bias (uniform and non-uniform bias). Measurement invariance was established; however, Item 1 was again problematic, resulting in only partial metric and scalar invariance. The scale was reliable (α ≥ 0.70). This study contributes to the limited research on the specific psychometric properties of the SWLS in a diverse Higher Education setting. The results could assist with valid and reliable measurement when developing interventions to enhance student well-being.