Linking scores on the 4- and 5-item versions 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

This study addresses how to compare scores on the Satisfaction With Life Scale (SWLS) when using a shorter, four-item version instead of the standard five-item version, particularly for people with traumatic injuries. The researchers used a method called "proration" to estimate what a person's score would be on the five-item scale if they only answered the four-item scale. This proration method involves adding the average of the four items' scores to the total of those four items, effectively imputing the missing fifth item.

• 1
  The study found that proration is a reliable way to link scores between the four-item and five-item versions of the SWLS in people with spinal cord injury (SCI), traumatic brain injury (TBI), and burn injury.
• 2
  The correlation between the prorated scores and the directly derived scores was very high (r = 0.97), and the intraclass correlation coefficient (ICC) indicated excellent reliability (ICC = 0.97).
• 3
  Most participants (93%) had score differences of less than 4 points between the prorated and directly derived scores, indicating good agreement between the two scoring methods.