The effect of images on item statistics in multiple choice anatomy examinations

Although multiple choice examinations are often used to test anatomical knowledge, these often forgo the use of images in favor of text-based questions and answers. Because anatomy is reliant on visual resources, examinations using images should be used when appropriate. This study was a retrospective analysis of examination items that were text based compared to the same questions when a reference image was included with the question stem. Item difficulty and discrimination were analyzed for 15 multiple choice items given across two different examinations in two sections of an undergraduate anatomy course. Results showed that there were some differences item difficulty but these were not consistent to either text items or items with reference images. Differences in difficulty were mainly attributable to one group of students performing better overall on the examinations. There were no significant differences for item discrimination for any of the analyzed items. This implies that reference images do not significantly alter the item statistics, however this does not indicate if these images were helpful to the students when answering the questions. Care should be taken by question writers to analyze item statistics when making changes to multiple choice questions, including ones that are included for the perceived benefit of the students. Anat Sci Educ 10: 68-78. © 2016 American Association of Anatomists.