Analysis Of Difficulty Index Of Single Best Response Type Of Multiple Choice Questions In Physiology By Post Validation

Abstract

Introduction: The most reliable format of objective evaluation is multiple choice questions (MCQs) which ideally should be drawn from a question bank of valid and tested MCQs. Difficulty index is one of the most important tool to assess the quality and validity of a MCQ and it signifies the difficulty level of that MCQ. Higher the difficulty index of an item, easier is the item and vice a versa.

Objectives: The objectives of the study were to find outdifficulty indexfor each item in a physiology MCQ test paper.

Materials and methods: Physiology MCQ test paper comprising of 40 items, with answer key and answer papers of 198 first MBBS students were obtained. 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 were determined using appropriate formula.

Results: Difficulty index of 25 MCQs was acceptable (P=30-70) of which 8 MCQs were ideal

(P=50-60%).11 MCQs were very easy (P>70%)& 4 MCQs were difficult (P<30%).

Discrimination index of 33 items was acceptable (0.2 & above) and of 7 items was poor

(below 0.2).

Conclusion: Valid MCQs with known difficulty index and acceptable discrimination index

Should be incorporated in MCQ bank. It will be helpful in future MCQ test paper setting and for