Title An assessment of functioning and non-functioning distractors in multiple-choice questions: A descriptive analysis

Background: Fouror five-option multiple choice questions (MCQs) are the standard in healthscience disciplines, both on certification-level examinations and on in-house developed tests. Previous research has shown, however, that few MCQs have three or four functioning distractors. The purpose of this study was to investigate non-functioning distractors in teacher-developed tests in one nursing program in an English-language university in Hong Kong. Methods: Using item-analysis data, we assessed the proportion of non-functioning distractors on a sample of seven test papers administered to undergraduate nursing students. A total of 514 items were reviewed, including 2056 options (1542 distractors and 514 correct responses). Nonfunctioning options were defined as ones that were chosen by fewer than 5% of examinees and those with a positive option discrimination statistic. Results: The proportion of items containing 0, 1, 2, and 3 functioning distractors was 12.3%, 34.8%, 39.1%, and 13.8% respectively. Overall, items contained an average of 1.54 (SD = 0.88) functioning distractors. Only 52.2% (n = 805) of all distractors were functioning effectively and 10.2% (n = 158) had a choice frequency of 0. Items with more functioning distractors were more difficult and more discriminating. Conclusion: The low frequency of items with three functioning distractors in the four-option items in this study suggests that teachers have difficulty developing plausible distractors for most MCQs. Test items should consist of as many options as is feasible given the item content and the number of plausible distractors; in most cases this would be three. Item analysis results can be used to identify and remove non-functioning distractors from MCQs that have been used in previous tests. Background Single best-answer multiple-choice questions (MCQs) consist of a question (the stem), two or more choices from which examinees must choose the correct option (the distractors) and one correct or best response (the key) [1]. The MCQ format allows teachers to efficiently assess large numbers of candidates and to test a wide range of content [2,3]. If properly constructed, MCQs are able to test higher levels of cognitive reasoning and can accurately discriminate between highand low-achieving students [2,4]. It is Published: 7 July 2009 BMC Medical Education 2009, 9:40 doi:10.1186/1472-6920-9-40 Received: 26 February 2009 Accepted: 7 July 2009 This article is available from: http://www.biomedcentral.com/1472-6920/9/40 © 2009 Tarrant et al; licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.