Rasch analysis of the UK Functional Assessment Measure in a sample of patients with traumatic brain injury from the UK national clinical database

OBJECTIVE To determine whether the UK Functional Assessment Measure (UK FIM+FAM) fits the Rasch model in patients with complex disability following traumatic brain injury. DESIGN Psychometric evaluation including preliminary exploratory and confirmatory factor analyses followed by Rasch analysis. PARTICIPANTS A multicentre UK national cohort of 1,956 patients admitted for specialist rehabilitation following traumatic brain injury. RESULTS The suitability of the Partial Credit Model was confirmed by the likelihood-ratio test (χ2 (df86) =7,325.0, p