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Wiley InterScience | ||||||
  Medical EducationVolume 39 Issue 3, Pages 284 - 291 Published Online: 23 Feb 2005 © 2010 Blackwell Publishing Ltd Published on behalf of the Association for the Study of Medical Education
Abstract | References | Full Text: HTML, PDF (Size: 160K) | Related Articles | Citation Tracking  assessment Assessment in the context of uncertainty: how many members are needed on the panel of reference of a script concordance test? Copyright 2005 Blackwell Publishing Ltd KEYWORDS education • medical • undergraduate/*standards • clinical competence/*standards • educational measurement/standards • physicians family • physicians role • reproducibility of results • Canada ABSTRACTPurpose The script concordance test (SCT) assesses clinical reasoning in the context of uncertainty. Because there is no single correct answer, scoring is based on a comparison of answers provided by examinees with those provided by members of a panel of reference made up of experienced practitioners. This study aims to determine how many members are needed on the panel to obtain reliable scores to compare against the scores of examinees. Methods A group of 80 residents were tested on 73 items (Cronbach's α: 0.76). A total of 38 family doctors made up the pool of experienced practitioners, from which 1000 random panels of reference of increasing sizes (5, 10, 15, 20, 25 and 30) were generated with a resampling procedure. Residents' scores were computed for each panel sample. Units of analysis were means of residents' score, test reliability coefficient and correlation coefficient between scores obtained with a given panel of reference versus the scores obtained with the full panel of 38. Statistics were averaged across the 1000 samples for each panel size for the mean and test reliability computations, and across 100 samples for the correlation computation. Results For sample variability, there was a 3-fold increase in standard deviation of means between a sample panel size of 5 (SD = 1.57) and a panel size of 30 (SD = 0.50). For reliability, there was a large difference in precision between a panel size of 5 (0.62) and a panel size of 10 (0.70). When the panel size was over 20, the gain became negligible (0.74 for 20 and 0.76 for 38). For correlation, the mean correlation coefficient values were 0.90 with 5 panel members, 0.95 with 10 members and 0.98 with 20 members. Conclusion Any number over 10 is associated with acceptable reliability and good correlation between the samples versus the full panel of 38. For high stake examinations, using a panel of 20 members is recommended. Recruiting more than 20 panel members shows only a marginal benefit in terms of psychometric properties. Received 21 November 2003; editorial comments to authors 20 February 2004, 21 April 2004; accepted for publication 8 June 2004 | 
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