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 discriminated power
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
Item analysis is done for obtaining: a) Difficulty value (D.V) b) Discriminative power (D.P)
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 availablemeans,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 NODISCRIMINATION The item of the test is answered correctly or know the answer by all the examinee’s An item is not answered correctly any of the examinee
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 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
Another method for discrimination index(D.I)If you take Likert scale for data collection The correlation between each item scores with totalscores.
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
General guidelines for difficulty value (D.V)Low difficulty value index means, that item is high difficulty one ex: D.V=0.20 » 20% only answered correctly for that item.So that item is too difficultHigh difficulty value index means, that item is easy one ex: D.V=0.80 » 80% answered correctly for that item. So thatitem is too easy one
Relationship between difficulty value anddiscrimination powerBoth (D.V & D.I) are complementary not contradictory to each otherBoth should considered in selecting good itemsIf an item has negatively discriminate or zero discrimination, is to berejected whatever the difficulty value
CRITERIA FOR SELECTION AND REJECTIONITEMS Positive discrimination index only selected Negative and zero discrimination index items are rejected High and low difficulty value items are rejected
REFERENCE Sharma R.A (2007);Essential of Scientific Behavioural Research, Meerut, Lall book depot. Mehta D.D (2011);Educational Measurement and Evaluation, Meerut, Tandon publication. Kulbir Singh Sidhu (2005);New Approaches to Measurement and Evaluation, New Delhi, Sterling Publishers. Akbar Husain (2012);Psychological Testing, New Delhi, Pearson.