Psychometric Properties of the Satisfaction With Life Scale in People With Traumatic Brain, Spinal Cord, or Burn...

This study evaluated the measurement properties of the Satisfaction With Life Scale (SWLS) in a sample of 17,897 people with spinal cord injury (48%, n = 8,566), traumatic brain injury (44%, n = 7,941), and burn injury (8%, n = 1,390), 1 year following injury. We examined measurement invariance across the groups, unidimensionality, local independence, reliability from a classical test and item response theory (IRT) framework, and fit to a unidimensional IRT model. The results support unidimensionality and local independence of the SWLS. Reliability was adequate from a classical test and IRT perspective. IRT analysis found that the SWLS could be improved by using only five response categories rather than seven and by removing the fifth item, "If I could live my life over, I would change almost nothing." This item functions poorly and reduces instrument reliability. With these revisions, the SWLS is a useful instrument to monitor an important outcome of trauma rehabilitation.