Standard setting Very Short Answer Questions (VSAQs) relative to Single Best Answer Questions (SBAQs): does having access to the answers make a difference?

Abstract

Background: We investigated whether question format and access to the correct answers affect the pass mark set by standard-setters on written examinations. Methods: Trained educators used the Angoff method to standard set two 50-item tests with identical vignettes, one in a single best answer question (SBAQ) format (with five answer options) and the other in a very short answer question (VSAQ) format (requiring free text responses). Half the participants had access to the correct answers and half did not. The data for each group were analysed to determine if the question format or having access to the answers affected the pass mark set. Results: A lower pass mark was set for the VSAQ test than the SBAQ test by the standard setters who had access to the answers (median difference of 13.85 percentage points, Z = -2.82, p = 0.002). Comparable pass marks were set for the SBAQ test by standard setters with and without access to the correct answers (60.65% and 60.90% respectively). A lower pass mark was set for the VSAQ test when participants had access to the correct answers (difference in medians -13.75 percentage points, Z = 2.46, p = 0.014). Conclusions: When given access to the potential correct answers, standard setters appear to appreciate the increased difficulty of VSAQs compared to SBAQs.