Are Difficulty Index and Discrimination Index Useful Tools For Assessing The Quality Of An MCQ? - A Cross Sectional Study.
European Journal of Molecular & Clinical Medicine,
2021, Volume 8, Issue 4, Pages 1672-1676
AbstractBackground: Good quality multiple choice questions (MCQs) can test knowledge of the students in depth which covers large syllabus in short time. MCQs if post validated accurately can give us items with known difficult index and discrimination index. However not many teaching institutes have provided adequate importance to item analysis.
Objectives: The objectives of the study were to find out difficulty index (P) and discrimination index (d) for each item in a physiology MCQ test paper.
Materials and methods: Physiology MCQ test paper comprising of 20 items, with answer key and answer papers of 250 first Year Physiotherapy students were obtained and item analysis was performed. Choice marked for each item by each student and his scores were entered in Microsoft Excel. Students were ranked & top 1/3rd and bottom 1/3rd were chosen as high achiever and low achiever group respectively. Difficulty index and discrimination index for each item was determined.
Results: 3 multiple choice questions were very difficult with difficulty index (p) <30%. 9 questions were within acceptable range of difficulty index (p- 30 to 70). 8 questions were easy with a difficulty Index (p) above 70%. Discrimination index (DI) of 6 out of 20 questions was below 0.20 and hence unacceptable. DI of 8 questions was between 0.20 to 0.25 and so acceptable. 4 questions were found to have a good discrimination index (DI= 0.25 to 0.35). 1 question was found to have excellent discrimination (DI= 0.35 or more). One item had negative discrimination index.
Conclusion: It can be concluded that difficulty Index (p) and discrimination Index (DI) are very useful tools for the assessment of the quality of an MCQ. An item with known and acceptable difficulty level and discrimination power should be preserved for future exams.
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