title: The high-level mobility assessment tool (HiMAT) for traumatic brain injury. Part 2: content validity and discriminability.
abstract: OBJECTIVE
  (i) To assess the measurement properties of the high-level mobility assessment tool (HiMAT) for people with traumatic brain injury (TBI), (ii) to measure the extent to which the HiMAT is a uni-dimensional, discriminative hierarchical outcome scale.
  
  
  METHODS
  The content validity was assessed using a three-stage process of investigating internal consistency, factor analysis and Rasch analysis. The uni-dimensionality of the HiMAT items was also tested. Discriminability was investigated by correlating raw and logit scores obtained from Rasch analysis. The study was conducted at a major rehabilitation facility using a convenience sample of 103 adults with TBI.
  
  
  RESULTS
  The internal consistency for the high-level items was very high (Cronbach's alpha = 0.99). Principal axis factoring identified several balance items as belonging to a second factor not related to high-level mobility, hence these items were excluded. Rasch analysis identified several misfitting items, such as walking around a figure of eight and stopping from a run, which were also excluded. Logit scores were used to exclude clustered and, therefore, redundant items. Raw scores correlated very highly (r = 0.98) with logit scores, indicating that raw scores provided good discriminability and were suitable for use by clinicians.
  
  
  CONCLUSIONS
  The HiMAT, which assesses higher-level mobility requirements of people with TBI for return to pre-accident social, leisure and sporting activities, is a uni-dimensional and discriminative scale for quantifying therapy outcomes.
authors.affiliation: Physiotherapy Department, Epworth Hospital, 89 Bridge Rd., Richmond 3121, Victoria, Australia. gavinw@epworth.org.au
authors.forename: G P
authors.initials: GP
authors.lastname: Williams
authors.forename: V
authors.initials: V
authors.lastname: Robertson
authors.forename: K M
authors.initials: KM
authors.lastname: Greenwood
authors.forename: P A
authors.initials: PA
authors.lastname: Goldie
authors.forename: M E
authors.initials: ME
authors.lastname: Morris
mesh_terms: D000328:Adult; D001930:Brain Injuries / Q000175:diagnosis* / Q000534:rehabilitation; D005260:Female; D005684:Gait; D006801:Humans; D008297:Male; D009069:Movement Disorders / Q000175:diagnosis*; D017063:Outcome Assessment, Health Care / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity