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Unit 10 : Item Analysis : Item Difficulty, Discrimination index, Effectiveness of Distractors

10.5.1 50% Top and 50% Bottom Group Right Response Method Notes
For example, a subject teacher wants to prepare a weekly objective test containing 10 items. He
has included 16 items in the initial draft and administered it on 10 students. In this case, the
difficulty index and discrimination index of this test will be calculated as follows :

Item Analysis Table

Item Student 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 Score
No.
1. Usha Pande 9 9 9 × 9 9 9 × 9 9 9 9 9 9 × 9 13*
2. Mukta Gulati 9 9 9 9 9 9 9 × 9 9 9 9 9 9 × 9 14*

3. Jnana Prakash 9 9 9 × 9 9 9 9 9 9 9 9 9 × × × 12*
4. Imran 9 9 9 9 9 9 × 9 9 9 9 9 9 × × 9 13*

5. Karuna × × × × × × 9 × × × × 9 9 9 9 9 6
6. Jitendra 9 9 9 9 × × × × × × × × × × × × 4

7. Sunil Tomar 9 9 9 9 9 9 × × × × × 9 9 9 9 9 11*
8. Rajendra 9 9 9 9 9 × × × × × × × × × × × 5

9. Amandeep 9 9 9 × × × × × × × × 9 9 9 9 9 8
10. Puja Chandela × × × × × × × 9 9 9 9 9 9 9 9 9 9

The total number of students is 10. Therefore, the top group and the bottom group will comprise
of 50% each, thus containing 5 students each. On arranging scores in descending order :
Scores Students
14 Mukta Gulati
13 Usha Pande
13 Imran
12 Jnana Prakash 50% superior group
11 Sunil Tomar
9 Puja Chandela
8 Amandeep
6 Karuna 50% inferior group
5 Rajendra
4 Jitendra

After this, right responses in each of superior group and inferior group will be counted for each
item. The number of right responses of each item will be divided by the total number of students
of each class, and the value obtained thus will be the difficulty index. It is clear from the above
table that Usha Pande, Mukta Gulati, Jnana Prakash, Imran and Sunil Tomar have answered
almost all questions correctly, so they have been placed in the superior group. On the other hand,
the remaining students : Karuna, Jitendra, Rajendra, Amandeep and Puja Chandela have answered
almost all questions wrongly, so they have been placed in the inferior group.

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