Item analysis: An evaluation of multiple choice questions in Physiology examination

Abstract

Background: Item analysis is the process of collecting, summarizing and using information from student’s responses to assess the quality of test items. Difficulty index and discrimination index are two parameters which help to evaluate the standard of multiple choice question (MCQ) used in an examination. Materials and Methods: An internal examination in Physiology was conducted at the end of one term. 148 students, out of 150, attended the exam. A total of 40 MCQ were given and analyzed. The data was analyzed by Microsoft Excel and recorded as mean ± standard deviation. The relationship between the difficulty index (P) and discrimination index (D) for each test item was determined by Pearson correlation analysis. Results: The mean difficulty index score was 0.54 ± 0.26 and mean discrimination score was 0.21 ± 0.14. On an average, about 10 of the MCQs were easy (P ≥ 70%) while 12 were difficult (P ≤ 30%) and the remaining 18 items were in acceptable range (P = 30-70%). In all, 2 items showed negative discrimination and 13 items exhibited poor discrimination. The remaining 25 items were in the range of acceptable to excellent discrimination. The discrimination index exhibited slight positive correlation with difficulty index (r = 0.3076 P = 0.05). However, it was not statistically significant. The maximal discrimination (d = 0.55) was observed with easy/difficult items (P = 0.6). Conclusion: The majority of the items were in acceptable range as far as difficulty and discrimination indices were concerned. Moderately easy/difficult items had the maximal discriminative ability. Too easy and too difficult items gave poor discrimination index.