ITEM ANALYSISDr. Rajasree

Lecturer in General Education

K.U.C.T.E,Aryad,Alappuzha

ITEM ANALYSIS

Item analysis is a statistical technique which is used for selecting and rejecting the items of the test on the basis of their difficulty value and discriminating power

 Item analysis is done for obtaining: Difficulty value (D.V) Discriminative power (D.P)

 

OBJECTIVES OF ITEM ANALYSIS: 

To select appropriate items for the final draft

To obtain the information about the difficulty value(D.V) of all

the items

To provide discriminatory power (D.I) to differentiate

between capable and less capable examinees for the

items

To provide modification to be made in some of the items

To prepare the final draft properly ( easy to difficult items

STEPS OF ITEM ANAYSIS: 

Arrange the scores in descending order

Separate two sub groups of the test papers

Take 27% of the scores out of the highest scores and 27% of

the scores falling at bottom

Count the number of right answer in highest group (R.H) and

count the no of right answer in lowest group (R.L)

Count the non-response (N.R) examinees

Difficulty value (D.V): 

“ The difficulty value of an item is defined as the

proportion or percentage of the examinees who have answered

the item correctly” -

J.P. Guilford

The formula for difficulty value (D.V )

D.V = (R.H + R.L)/ (N.H + N.L)

R.H – rightly answered in highest group, R.L - rightly answered

in lowest group N.H – no of examinees in highest group, N.L -

no of examinees in lowest group

In case non-response examinees available means, The formula for

difficulty value (D.V)

D.V = (R.H + R.L)/ [(N.H + N.L)- N.R]

R.H – rightly answered in highest group

R.L - rightly answered in lowest group

N.H – no of examinees in highest group

N.L - no of examinees in lowest group

N.R – no of non-response examinees

Discrimination index (D.I): 

“ Index of discrimination is that ability of an item on the

basis of which the discrimination is made between superiors and

inferiors ” –

Blood and Budd

(1972)

Types of discrimination index (D.I): 

Zero discrimination or No discrimination

Positive discrimination

Negative discrimination

Zero discrimination or No discrimination : 

Zero discrimination or No discrimination: The item of the test is

answered correctly or know the answer by all the examinee’s An

item is not answered correctly by any of the examinee

Positive discrimination index: 

Positive discrimination index :An item is correctly answered by

superiors and is not answered correctly by inferiors. The

discriminative power range from +1 to -1.

Negative discrimination index: 

Negative discrimination index :An item is correctly answered by

inferiors and is not answered correctly by superiors.

The formula for discrimination index(D.I)

D.I = (R.H - R.L)/ (N.H or N.L)

R.H – rightly answered in highest group

R.L - rightly answered in lowest group

N.H – no of examinees in highest group

N.L - no of examinees in lowest group

General guidelines for discriminating index (D.I)

According to Ebel , D.I Item Evaluation

≥0.40 -Very good items

0.30 - 0.39 Reasonably good but subject to

improvement

0.20 – 0.29 Marginal items , need improvement

<0.19 Poor items . Rejected or revised

D.V Item Evaluation

0.20 – 0.30 Most difficult

0.30 - 0.40 Difficult

0.40 – 0.60 Moderate difficult

0.60 – 0.70 Easy

0.70 – 0.80 Most easy

Relationship between difficulty value and discrimination power

Both (D.V & D.I) are complementary not contradictory to each other

Both should be considered in selecting good items

If an item has negatively discriminate or zero discrimination, is to be

rejected whatever be the difficulty value

THANK YOU