Item analysis ppt

item analysis which is use for rejecting & accepting the test of items....it is helpful for education & research.

1. ITEM ANALYSIS PRESENTED BY: Ms . Preeti Sharma Msc(N ) Prev Yr

2. INTRODUCTION It is a statistical technique which is used for selecting and rejecting the items of a test on the basis of their difficulty value and discriminative power. Item analysis technique helps in selecting the best items for final draft of the test and poor items are rejected and the items are modified.

3. In addition, item analysis is valuable for increasing instructors’ skills in test construction, and identifying specific areas of course content which need greater emphasis or clarity. The procedure used to judge the quality of an item is called as item analysis.

4. “ It 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”. “Item analysis is an aspect of test analysis which involves examination of the characteristics of test items.” “The effectiveness of each item can be determined by analyzing the pupils response to the item, this is known as item analysis.”

5. PURPOSES To judge the worth or quality of a test Classification of students or candidates. Selection of the candidates for the job. Promoti o n an d prog n osis o f the can d i d a t es or student To do modification to be made in some of the items.

6. Brings ab o ut i mpr o vement i n test i ng m eth o ds and techniques. Make d e cis i o n s abo u t pr o m o t i on o f s t u d e n ts to the next higher grade To provide discriminatory power to differentiate between capable & less capable examinees for the items. To prepare the final draft on the basis of their difficulty level properly (easy to difficult items).

7. OBJECTIVES To select the appropriate items for the final draft and reject the poor items which do not contribute in the functioning of the test. Some items are to be modified. Item analysis obtains the difficulty values of all items of preliminary draft of the test. The items are classified difficult, moderate, easy items It provides the discriminative power (item reliability/ validity) to differentiate between capable and less capable examinees of all the items.

8. The reliability and validity of test depends upon the characteristics of test. Both these indexes are considered simultaneously in selecting and rejecting the items of a test. Item analysis is a cyclic technique. The modified items are tried out and their items analysis is done again to obtain these indexed (difficulty and discrimination). The empirical evidences are obtained for selecting the items for the final draft.

9. STEPS Arrange the scores in descending order Separate two sub groups of the test papers Take 27% of the scores out of the higher scores and 27% of the scores falling at bottom Count the number of examinees in higher (N.H) and lower group (N.L) Count the number of right answer in higher group (R.H) and count the number of right answer in lower group (R.L) Count the non response (N.R) examinees.

10. It involves three numerical indicators. They are: Item Difficulty value Item Discrimination power Distracter Power

11. ITEM DIFFICULTY VALUE (D.V) “ The d i f fi c u l ty va l ue o f a n item is de f i n ed a s t h e proportion or percentage of the examinees who have answered the item correctly” - J.P. Guilford

12. Formula : R .H= rightly answered in higher group R.L= rightly answered in lower group N.H= no. of examinees in higher group N.L = no . of examinees in lower group D.V = (R.H+ R.L) (N.H+ N.L)

13. I.D = R/ N X 100 R= Rightly answered in group N= total no. of examinees

14. In case of non- response examinees available means, R.H= rightly answered in higher group R.L= rightly answered in lower group N.H= no. of examinees in higher group N.L= no. of examinees in lower group N.R= no. of non- response examinees D.V= (R.H+ R.L) (N.H+ N.L )- N.R

15. Level of Difficulty Index Range Difficulty Level 0.00-0.20 Very Difficult 0.21-0.40 Difficult 0.41-0.60 Average/Moderately Difficult 0.61-0.80 Easy 0.81-1.00 Very Easy

16. ITEM DISCRIMINATION INDEX ( D .I ) “ Index of discrimination is that ability of an item on the bas i s o f whic h the discriminati o n i s made b e t w een superiors and inferiors ”. It range from +1 to -1. - Blood and Budd (1972)

17. R.H= rightly answered in higher group R.L= rightly answered in lower group N.H= no. of examinees in higher group N.L= no. of examinees in lower group D.V = (R.H+ R.L) (N.H ) or N.L

18. Types of Discrimination Index Positive Discrimination Negative Discrimination Zero Discrimination

19. Positive Discrimination An item is correctly answered by superiors & is not answered correctly by inferiors. Negative Discrimination An item is correctly answered by inferiors & is not answered correctly by superiors.

20. Zero discrimination / No discrimination The item of the test is answered correctly by all the examinee’s or an item is not answered correctly by any of the examinee.

21. Ebel’s (1972) gives the indices of item discrimination in the terms shown below. For average classroom test, these indices are widely accepted. D Value Item Evaluation 0.40 and above very good item 0.30 – 0.39 reasonably good, but subject to improvement 0.0 – 0.29 marginal items usually needing and being subject to Improvement Below 0.19 poor items to be rejected or improved by revision

22. DISTRACTOR POWER The third statistic is distractor power. It provides information about effectiveness of the distractors Groundlund and Linn 1990 states that this can be determined by inspection and so there is no need to calculate index In general a good distractor should discriminate between upper and lower groups

23. EAMPLE: TOTAL A B C D E N.H 27 7 17 1 2 N.L 27 3 7 8 9

24. CONCLUSION Thus item analysis is an effective way to select the appropriate items for the final draft & reject the poor items which do not contribute in the functioning of the test.