title: The Mayo-Portland Participation Index: A brief and psychometrically sound measure of brain injury outcome.
abstract: OBJECTIVE
  To evaluate the internal consistency, interrater agreement, concurrent validity, and floor and ceiling effects of the 8-item Participation Index (M2PI) of the Mayo-Portland Adaptability Inventory (MPAI).
  
  
  METHODS
  M2PI data derived from MPAIs completed independently by the people with acquired brain injury undergoing evaluation, their significant others, and rehabilitation staff were submitted to Rasch Facets analysis to determine the internal consistency of each independent rater group and of composite measures that combined rater groups. Correlations with the full-scale MPAI were examined to assess concurrent validity, as was interrater agreement.
  
  
  METHODS
  Outpatient rehabilitation in academic physical medicine and rehabilitation department.
  
  
  METHODS
  People with acquired brain injury (N=134) consecutively seen for evaluation, significant others, and evaluating staff.
  
  
  METHODS
  Not applicable.
  
  
  METHODS
  The MPAI and M2PI.
  
  
  RESULTS
  The M2PI showed satisfactory internal consistency, concurrent validity, interrater agreement, and minimal floor and ceiling effects, although evidence of rater bias was also apparent. Composite indices showed more desirable psychometric properties than ratings by individual rater groups.
  
  
  CONCLUSIONS
  The M2PI, particularly in composite indices and with attention to rater biases, provides an outcome measure with satisfactory psychometric qualities and the potential to represent the varying perspectives of people with acquired brain injury, significant others, and rehabilitation staff.
authors.affiliation: Department of Psychiatry and Psychology, Mayo Clinic College of Medicine, Rochester, MN 55905, USA. malec.james@mayo.edu
authors.forename: James F
authors.initials: JF
authors.lastname: Malec
mesh_terms: D000223:Adaptation, Psychological; D000293:Adolescent; D000328:Adult; D000368:Aged; D001930:Brain Injuries / Q000523:psychology* / Q000534:rehabilitation*; D017028:Caregivers; D005260:Female; D006282:Health Personnel; D006305:Health Status Indicators; D006801:Humans; D008297:Male; D008875:Middle Aged; D008910:Minnesota; D011594:Psychometrics; D015203:Reproducibility of Results