title: Hawks, Doves and Rasch decisions: Understanding the influence of different cycles of an OSCE on students' scores using Many Facet Rasch Modeling.
abstract: BACKGROUND
  OSCEs are commonly conducted in multiple cycles (different circuits, times, and locations), yet the potential for students' allocation to different OSCE cycles is rarely considered as a source of variance-perhaps in part because conventional psychometrics provide limited insight.
  
  
  METHODS
  We used Many Facet Rasch Modeling (MFRM) to estimate the influence of "examiner cohorts" (the combined influence of the examiners in the cycle to which each student was allocated) on students' scores within a fully nested multi-cycle OSCE.
  
  
  RESULTS
  Observed average scores for examiners cycles varied by 8.6%, but model-adjusted estimates showed a smaller range of 4.4%. Most students' scores were only slightly altered by the model; the greatest score increase was 5.3%, and greatest score decrease was -3.6%, with 2 students passing who would have failed.
  
  
  CONCLUSIONS
  Despite using 16 examiners per cycle, examiner variability did not completely counter-balance, resulting in an influence of OSCE cycles on students' scores. Assumptions were required for the MFRM analysis; innovative procedures to overcome these limitations and strengthen OSCEs are discussed.
  
  
  CONCLUSIONS
  OSCE cycle allocation has the potential to exert a small but unfair influence on students' OSCE scores; these little-considered influences should challenge our assumptions and design of OSCEs.
authors.affiliation: a School of Medicine, Keele University , Stoke-on-Trent , UK.
authors.forename: Peter
authors.initials: P
authors.lastname: Yeates
authors.affiliation: b Faculty of Education, Queen's University, Kingston , Ontario , Canada.
authors.forename: Stefanie S
authors.initials: SS
authors.lastname: Sebok-Syer
mesh_terms: D002983:Clinical Competence; D004504:Education, Medical, Undergraduate / Q000379:methods* / Q000592:standards*; D004521:Educational Measurement / Q000379:methods* / Q000592:standards*; D006801:Humans; D015588:Observer Variation; D011340:Problem Solving; D015203:Reproducibility of Results; D013997:Time Factors