Decreasing the options’ number in multiple choice questions in the assessment of senior medical students and its effect on exam psychometrics and distractors’ function

Abstract

Background Studies that have investigated the effect options’ number in MCQ tests used in the assessments of senior medical students are scarce. This study aims to compare exam psychometrics between three- and five-option MCQ tests in final-year assessments. Methods A cluster randomized study was applied. Participants were classified into three groups, according to their academic levels. Students in each of those levels were randomized into either the three- or five-option test groups. Results Mean time to finish the five-option test was 45 min, versus 32 min for the three-option group. Cronbach’s alpha was 0.89 for the three-option group, versus 0.81 for the five-options, p-value = 0.19. The mean difficulty index for the three-option group was 0.75, compared to 0.73 for the five-option group, p-value = 0.57. The mean discriminating index was 0.53 for the three-option group, and 0.45 for the five-options, p-value = 0.07. The frequency of non-functioning distractors was higher in the five-option test, 111 (56%), versus 39 (39%) in the three-options, with p-value < 0.01. Conclusions This study has shown that three-option MCQs are comparable to five-option MCQs, in terms of exam psychometrics. Three-option MCQs are superior to five-option tests regarding distractors’ effectiveness and saving administrative time.