A brief measure of life satisfaction : psychometric properties and measurement invariance of the Polish three-item Satisfaction with Life Scale (SWLS-3)

Kurzfassung/Abstract

Background:
The Satisfaction with Life Scale-3 (SWLS-3) is a brief three-item version of the five-item Satisfaction with Life Scale (SWLS), but it has not been validated in Poland. This study examined its psychometric properties, structural validity, measurement invariance across sex and between the Polish and original UK samples, and convergent validity with well-being, gratitude, awe, and forgiveness.

Participants and procedure:
A total of 506 Polish-speaking adults (Mage = 27.70, SD = 7.72; 58.1% women) completed an online survey including the SWLS, the World Health Organization Five Well-Being Index (WHO-5), the Gratitude/Awe Questionnaire, and the Toussaint Forgiveness Scale. Structural validity was assessed by testing the fit of the hypothesized model. Measurement invariance across sex and samples was examined. Internal consistency was evaluated using Cronbach’s alpha (α) and McDonald’s omega (ω). Convergent and discriminant validity were assessed through associations with related constructs.

Results:
The SWLS-3 demonstrated good model fit. It showed configural, metric, and scalar invariance across sex. Across samples, metric invariance was supported, but scalar invariance was not achieved. Internal consistency was acceptable (α = .78, ω = .79). Scores were positively associated with well-being, gratitude and awe, and forgiveness.

Conclusions:
The SWLS-3 is a reliable and valid brief measure of life satisfaction, suitable for large-scale research, including cross-cultural research on associations, although caution is needed when comparing mean scores across countries.