title: Demonstrating Construct Validity of the American Board of Physical Medicine and Rehabilitation Part I Examination: An Analysis of Dimensionality.
abstract: BACKGROUND
  Ideally, high-stakes examinations assess 1 dimension of medical knowledge to produce precise estimates of a candidate's performance. It has not been reported whether the American Board of Physical Medicine and Rehabilitation Part 1 Certification Examination (ABPMR-CE-1) is unidimensional or not.
  
  
  OBJECTIVE
  To examine the ABPMR-CE-1 to measure how many dimensions it assesses.
  
  
  METHODS
  Retrospective observational study.
  
  
  METHODS
  We assessed examination results from the 2015 ABPMR-CE-1.
  
  
  METHODS
  A total of 489 deidentified candidates taking the 2015 ABPMR-CE-1.
  
  
  METHODS
  A 1-parameter Item Response Theory (IRT) measurement model was utilized. A Principal Components Analysis (PCA) of standardized residual correlations was used to detect multidimensionality.
  
  
  METHODS
  Number of primary dimensions reflected in the 325 test questions.
  
  
  RESULTS
  The results of the dimensionality analysis indicated that the ABPMR-CE-1 examination is highly unidimensional from a psychometric perspective. Expert content review of the substantive content of small contrasting clusters of questions provided additional assurance of the unidimensional nature of the examination.
  
  
  CONCLUSIONS
  The ABPMR-CE-1 appears indeed to measure a single construct, which suggests a sound structure of the examination. It closely approximates the assumption of statistical unidimensionality.
  
  
  METHODS
  Not applicable.
authors.affiliation: American Board of Physical Medicine and Rehabilitation, Rochester, MN(∗).
authors.forename: Mikaela M
authors.initials: MM
authors.lastname: Raddatz
authors.affiliation: University of Toronto, Division of Physical Medicine and Rehabilitation, Toronto, ON, Canada; St. John's Rehab, S125, 285 Cummer Ave, Toronto, ON M2M 2G1, Canada(†). Electronic address: Larry.Robinson@Sunnybrook.ca.
authors.forename: Lawrence R
authors.initials: LR
authors.lastname: Robinson
mesh_terms: D002568:Certification / Q000379:methods*; D002983:Clinical Competence; D004521:Educational Measurement; D005260:Female; D006801:Humans; D008297:Male; D010810:Physical and Rehabilitation Medicine / Q000193:education*; D011594:Psychometrics; D015203:Reproducibility of Results; D012189:Retrospective Studies; D013044:Specialty Boards / Q000592:standards*; D014481:United States