Page 139 - DEDU504_EDUCATIONAL_MEASUREMENT_AND_EVALUATION_ENGLISH

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

Validity Index Table Notes
Item No. Number of right Number of right Degree of
responses in responses in inferior (V.I. = R –R ) Value Validity
H L
superior group (R ) group(R )
H L
1. 5 3 +2 Ordinary
2. 5 3 +2 Ordinary
3. 5 3 +2 Ordinary
4. 3 2 +1 Bad
5. 5 1 +4 Very good
6. 5 0 +5 Best
7. 2 1 +1 Bad
8. 3 1 +2 Ordinary
9. 4 1 +3 Good
10. 4 1 +3 Good
11. 4 1 +3 Good
12. 5 3 +2 Ordinary
13. 5 3 +2 Ordinary
14. 3 3 0 Very bad

15. 1 3 – 2 Negative
16. 4 3 +1 Bad
It is clear from the above table that the V.I. of the 15th item is negative. It means that the number
of right responses in the inferior group is more than the number of right responses in the
superior group. Therefore, this item is not suitable and it should not be included in the final draft
of the test. In the same way, the discriminating value of 14th item is zero, which means that this
question cannot discriminate between good and bad students, because both types of students can
attempt it correctly, and from this viewpoint, this is not suitable for inclusion in the final test.
Besides, the discriminating value of 4th, 7th and 16th questions is not satisfactory, so they will
have to be excluded from the final draft. The remaining questions can be selected in the final
draft with regard to their difficulty index and discriminating value.

Selection of Items for Final Form of the Test
Item No. Difficulty Index Discriminating Value Result

1. .80 + 2 Selected
2. .80 + 2 Selected
3. .80 + 2 Selected
4. .50 + 1 Excluded
5. .60 + 4 Selected
6. .50 + 5 Selected
7. .30 + 1 Excluded
8. .40 + 2 Selected
9. .50 + 3 Selected

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