Psychometric Properties of the Satisfaction With Life Scale in People With Traumatic Brain, Spinal Cord, or Burn Injury: A National Institute on Disability, Independent Living, and Rehabilitation Research Model System Study

TitlePsychometric Properties of the Satisfaction With Life Scale in People With Traumatic Brain, Spinal Cord, or Burn Injury: A National Institute on Disability, Independent Living, and Rehabilitation Research Model System Study
Publication TypeJournal Article
Year of Publication2017
AuthorsAmtmann D, Bocell FD, Bamer A, Heinemann AW, Hoffman JM, Juengst SB, Rosenberg M, Schneider JC, Wiechman S, McMullen K
JournalAssessment
Start Page1
Pagination1-11
Date Published02/2017
Keywordsburn injury, item response theory, measurement invariance, Satisfaction With Life Scale, spinal cord injury, traumatic brain injury
Abstract

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.