Item difficulty & item discrimination as quality indicators of physiology MCQ examinations at the Faculty of Medicine Khartoum University

Abstract

Background: Item analysis is an essential tool used in the evaluation of the quality of MCQ examinations. Objectives: This study aimed at assessing the quality of items of physiology MCQ examinations at the Faculty of Medicine, Khartoum University, using post-examination item analysis. Methods: A descriptive, cross-sectional study was carried-out on test statistics reports using Remark- software which provides analysis of students’ responses in the form of Excel file formats. Ten physiology MCQ exams held from September 2015 - September 2016 were included in the study. Each exam paper consisted of 60-80 (five-option) items. Item Difficulty index [DIF I] and Discrimination Index (DI) (using point biserial correlation coefficient/ r pbis ) were measured as quality indicators. Results: The mean DIF I of 645 items was (56.01±19.97) & the mean r pbis was (0.37±0.13). The majority of items (63.3%) were of acceptable difficulty; (25.5%) were easy & (11.1%) were difficult. The highest proportion (43.5%) of items were excellent; followed by (30%) good; (16.6%) acceptable and (9.6%) poor discriminating items. There were only 5 negatively discriminating items that constituted 0.8% out of total items. The relationship between difficulty and discrimination indices was dome-shaped with maximal discrimination at acceptable difficulty level. Conclusion: Generation of high quality examinations with average difficulty and good discrimination power is the outcome of careful construction and meticulous review of exams’ items by our expert staff members. Maximizing exam discrimination is achieved by reducing the number of the very difficult and very easy items.