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Formula for Discrimination Index

Number of Students in High Marks group ( RH ) with the Correct Answer

Minus (-)

Number of Students in Low Marks group (RL) with the Correct Answer

Divided by

Half the total number of Students who attempted the question ( T )

= RH RL

T

Interpretation of the Discrimination Index

Value Description Suggestion_______

0.40 high discrimination Question is retained

0.20 -0.39 moderate discrimination Question is checked and revised

0.10- 0.19 low discrimination Question is removed of rewritten

0.00 & negative no discrimination Question is removed

DISCRIMINATION INDEX FOR ITEM 1 -15

Item 1

A* B C D

12 5 0 3

7 3 4

(20) = 10 = 0.4

Item 1 is of high discrimination so

question is retained.

Item 9

A B* C D

2 8 4 6

5 -2 = 3

1/2 (20) 10 = 0.3

Item 2 is of moderate discrimination so

question needs to be checked and revised.

Item 2

A B C D*

1 13 2 4

10 -3 = 7

Item 10

A B C D*

7 1 1 1

5-4 1

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1/2 (20) 10 = 0.35

Item 2 is of moderate discrimination so

question needs to b checked and revised.

(20) = 10 = 0.1

Item is of low discrimination so question has

to be removed or rewritten.

Item 3

A B C* D

2 1 16 1

7-6 1

(20) = 10 = 0.1

Item is of low discrimination so question has

to be removed or rewritten.

Item 11

A B C D*

0 14 1 5

3-3 0

(20) = 10 = 0.0

There is no discrimination so question is

removed.

Item 4

A B C D*

8 2 2 8

5-2 3

(20) = 10 = 0.3

Moderate discrimination . Question is

checked or revised

Item 12

A B C* D

0 7 7 6

4 3 1

(20) = 10 = 0.1

Item is of low discrimination so question is

removed or rewritten.

Item 5

A B C D *3 1 2 14

8 4 4

(20) = 10 = 0.4

Item is of high discrimination so question is

retained

Item 13

A B C D*4 3 0 13

8- 2 = 6 =0.6

(20) 10

Item is of high discrimination so question is d

retained.

Item 6

A B C D*

0 3 2 15

8-5 = 3 = 0.3

(20) 10 = 0.3

Item is of moderate discrimination so

Item 14

A B C* D

2 4 14 0

9-3 = 6 = 0.6

(20) 10

Question is of high discrimination so

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question is checked and revised. Question is retained .

Item 7

A B C D *

3 6 2 9

5-4 = 5-4 = 0.1

(20) 10

Question is of low discrimination . Question

is removed or rewritten.

Item 15

A B C D *

0 6 10 4

2-2 = 0 = 0.0

(20) 10

Question is of no discrimination so question

is removed .

Item 8

A B C D*

1 3 8 8

7 0 7

(20) = 10 = 0.7

Item 1 is of high discrimination so

question is retained.

2.2.2 Summary of the Discrimination Index

Based on the calculation items 1,5, 8, 13 and 14 are of high discrimination so are gooditems and should be retained. Meanwhile, items 2, 4,6,9 and moderate items. They should be

retained. However, the items could be further improved in terms of rephrasing the stems or the

options if necessary. Item 3, 7,10 and 12 are of low discrimination . If questions are going to be

administered again, they need to be rephrased or improved. Finally, there is no discrimination for

Item 11 and 15 so both questions need to be removed . If content knowledge of those items are

needed, the stems and options for both items need to be rewritten.