Measurement Invariance and Validity of the Satisfaction With Life Scale in Informal Caregivers

Background: The number of informal caregivers within ageing population is increasing and there is a growing research interest to promote their wellbeing, and therefore there is a need for adequate measurement tools. We aim to provide validity evidence of the Satisfaction with Life Scale (SWLS) in a representative sample of British older adults, including measurement invariance across caregivers and non-caregivers. Method: Data was drawn from English Longitudinal Study of Ageing (ELSA). The sample consisted of 3,754 caregivers and 4,036 non-caregivers. The structure and measurement invariance were tested through a confirmatory factor analysis. Reliability and validity evidence based on relationships with other variables were also analysed. Results: Our results supported the one factor structure of the SWLS, CFI = .996; NNFI = .993; RMSEA = 0.081, and measurement invariance across caregiving status. McDonald's omega was .93. Scores on the SWLS were positively correlated with quality of life, positive social support, and self-reported health, and negatively with loneliness, depression, negative social support, difficulties in activities and instrumental activities of daily living, and number of health conditions. Conclusions: These findings provide new psychometric evidence to support the use of the SWLS in research which focuses on caregivers and on the comparison with non-caregiver samples.

Automated summary

This study provides validity evidence for the use of SWLS in a representative sample of British older adults, including measurement invariance across caregivers and non-caregivers. These findings are important for research focusing on caregivers and the comparison with non-caregiver samples.