assessment of distracters in multiple-choice tests

background: the aim of using distracters in multiple-choice questions (mcqs) is to distract those who don t know the correct answer of the question. the mcqs must be designed in a way that the students who have reached the pre-determined educational objectives, have a better chance in finding the correct answer than those who have not. therefore, a question has an appropriate efficacy when more low-grade students are attracted to the distracters than high-grade students. purpose: considering the important role of distracters in differentiating between low and high-grade students, this research studies the distracters in the multiple-choice tests (mcts) given in mashad medical school in the first semester of 2001-2002. method: in this descriptive study, the data of 21 mcts performed in one semester were collected and recorded by optical mark reader (omr). from 1281 questions, 612 mcq questions were sampled randomly, and the numbers of low and high-grade students choosing the distracters were compared and analyzed using spss software. results: the efficacy of 45.9% of distracters was relatively weak to extremely weak , with relatively weak , weak , very weak and extremely weak distractors having a prevalence of 11.4%, 10%, 15.1% and 9.4% respectively. extremely weak distracters were those that had a negative impact. which means the high-grade students were more attracted than the low-grades. of the mcqs, 42.7% had one, and one third of the questions had two weak distracters. among all 6 questions, only 15.1% had three good distracters. conclusion: our study showed that more than half of he distracters had a weak quality. so we suggested that before performing a test, the experts opinion about the designed questions should be obtained and considered to minimize the technical problems of the questions.