Rasch analysis of the Satisfaction with Life Scale across countries: Findings from South Africa and Italy

The Satisfaction with Life Scale (SWLS) is widely used to assess global satisfaction with life. Although the scale’s psychometric properties were extensively investigated through different methods, Rasch analysis can provide further insight into the scale’s targeting and sensitivity across the different levels of the underlying construct. It also allows researchers to evaluate how well a scale fits the assumptions of unidimensionality and local independence of the items, how the response categories are used, and whether differential item functioning occurs in different demographic groups. In this study, Rasch analysis was used to examine the psychometric properties of the SWLS among participants from South Africa (n = 676) and Italy (n = 516). Findings showed that the scale was insensitive at high levels of life satisfaction. Since the majority of the participants reported high scores, these results suggest that the SWLS may not be sensitive to detect change in the general population. Although support was provided to the scale’s unidimensional factor structure, a distinction emerged between items referring to satisfaction with present and past life. No group difference in item functioning was detected for country, gender, age group, or education level. However, findings suggest that using fewer response categories with less nuanced lower level descriptors could be more appropriate, especially for the South African sample. Overall, results highlight the need for further research on the SWLS, especially concerning insensitivity at the upper range.