Test-Retest: Intra class correlations (ICC) from a subsample of 381 participants ranged from 0.78 (emotions) to 0.85 (physical problems), indicating good test-retest reliability. The overall score was 0.91 (CI 0.89 to 0.92) (van Steinbuchel et al. 2010). Van Steinbuechel (2015) found good test-retest reliability among participants with TBI using intraclass correlation (ICC)=0.81.

Internal Consistency: Internal consistency was assessed for each of the subscales in each language. Cronbach’s scores ranged from 0.75 (physical problems subscale) to 0.89 (cognition and self-subscales). Internal consistency was also found when looking at scores of those with MMSE scores of <28 and comparing them to those with an MMSE score of >27. was 081 for the physical problems subscale for the group with low cognitive performance, and 0.76 for those with normal cognitive status (von Steinbuchel et al. 2010). Although the QOLIBRI total score is useful as an overall summary, the analysis indicates that it does not completely describe variation in HRQoL and that this is more fully and consistently measured by the profile of individual scales. Van Steinbuechel (2015) found good internal consistency among participants with TBI using Cronbach’s α=0.86.

Concurrent Validity: There was a significant relationship between the QOLIBRI and the Glasgow Outcome Scale Extended (GOSE). The strongest relationship was with the subscale daily life and autonomy (r=0.42) and the weakest was with the emotions subscale (r=0.19). Those with a good recovery reported more areas as good on the HRQoL than those with moderate or severe injuries. The relationship between the HADS and the QOLIBRI was also found to be strong, with the strongest relationship between the HADS depression scale the self-scale (r=-0.62) and the HADS anxiety scale the emotions scale (r=-0.62). The SF PCS was strongly related to the physical problems scale (r=0.63) and the SF MCS was strongly associated with the emotions scale (r=0.61).

Construct Validity: Further analysis revealed the outcome related information captured by the SF-36 mental health component score was also captured by the QOLIBRI.

Construct Validity (Known Groups): Effects of age (r=-0.06), education (r=0.11), time since injury (r=-0.08) and the severity of injury as determined by the GCS (r=-0.03) were all very weak. Current comorbid health conditions showed a significant relationship with all QOLIBRI subscales with the strongest correlation (r-0.56) on the physical subscale. An association between the test scores and the QOL of the person was found. Van Steinbuechel (2015) found good construct validity in the group with TBI.