The relationship between item difficulty and Non-Functioning distractors of multiple choice questions

Multiple choice questions (MCQs) are widely used for assessing student learning in universities. Item analysis is performed for assessing the quality of test items. Analysing the distractors is essential in order to determine if they are functioning.

The study aimed at performing item analysis of three MCQs exams and finding the relationship between the item difficulty and the number of non-functioning distractors.

The 98 MCQs and 294 distractors used in the three exams: a child health nursing and two genetics in nursing exams, attended by a total of 178 students of a College of Nursing in Saudi Arabia, were analysed.

Overall, the 98 MCQs had average mean difficulty index (68.26) and over half of the total items (55.10) were easy. The mean discrimination index was 0.28. More than one third (38.73%) of the 294 distractors were NFDs. The difficulty index correlated significantly with NFDs, collectively on the exams (r=0.555; p<0.001) as well as on individual tests. ANOVA showed that as the number of NFDs increased, the difficulty index (easiness) of the test increased. The study therefore confirmed that NFDs influence the quality of the test items by making the test easy for examinees.

Generating high-quality items is an important aspect of the educational assessment. Analyzing items and finding the relationship between the difficulty index and the NFDs is essential. MCQs that have more number of NFDs tend to be easier than those with fewer NFDs. The results of the study will provide an opportunity for faculty to improve the development and use of MCQ tests.