Item analysis in education
- 1. ITEM ANALYSIS Presented by: Muhammad Munsif Role number: msf1900315 Presented to: Muhammad ANWAR munsifsail@gmail.com M.Phil. education (Evening 2019-2021)
- 2. Target 1 Target 2
- 4. Item analysis Item analysis is a statistical technique, used for selecting and rejecting the items of the test on the basis of their difficulty value and discrimination power.
- 5. Types of Item Analysis Qualitative item analysis Quantitative item analysis It is the process in which teacher or expert does the proof reading before administering the test to check structure and grammatical mistakes errors. It contains the numeric values for the test item analysis, we often find numerical indicators during quantitative item analysis.
- 6. Purpose of Test Analysis ● to select appropriate items ● to obtain the information about the difficulty level of all the items ● to provide discriminatory power to differentiate between capable and less capable examinees for the items ● to provide modification in some of the items ● to prepare the final draft properly ( easy to difficult items)
- 7. Why item analysis is important? Item analysis data provide a basis for • efficient class discussion of test results • remedial work • the general improvement of class instruction • increased Skill in test construction
- 8. Determining item effectiveness Item analysis is usually designed to answer the following questions: ● Did the item function as intended? ● Was the item of appropriate difficulty? ● Was the test item free of irrelevant clues and other defects? ● Was each of the distractor effective?
- 9. Item difficulty and discrimination ● Item analysis provides important information about how well items function. ● It helps us to know the degree to which students get the answer correct. ● Item discrimination examines how the top scoring group of test takers performed as compared to the lowest scoring group.
- 10. Difficulty level index( p) “The item difficulty is simply the percentage of students who answer an item correctly.” Low difficulty value= Difficult item High difficulty value= Easy item
- 11. ● If an item is answered correctly by 90% of the examinees, it means the item is very easy. ● If an item is answered correctly by 30% of the examinees, it means the item is very difficult. ● Item with difficulty level of 50% is considered best to be included in the test.
- 12. Statistical Calculation of Item Difficulty Extreme Group method ● Number of examinees should ranked from highest to lowest on the basis of scores. ● Upper 27% and Lower 27% may be separated for the purpose. ● Middle 46% are set aside and only on the basis of 54% the index of difficulty of each item is determined.
- 13. How is item difficulty calculated? ● To compute the item difficulty, divide the number of people answering the item correctly by the total number of people answering the item. The proportion for the item is usually denoted as p and is called item difficulty (Crocker & Algina, 1986). ● The higher the difficulty level, the easier the item is and vice versa.
- 14. ● Item difficulty ranges from 0.25 to 0.75 is the best. ● Below 0.25 means item is very difficult and above 0.75 shows that the item is very easy. ● Example: 6/10=0.60 ● Also referred to as the p-value
- 15. Item Discrimination(D) “Item discrimination refers to the ability of an item to differentiate between high-achievers and low-achievers.
- 16. Discrimination index calculation 1. Divide the group of test takers into two groups high scoring and low scoring. 2. Count the correct responses of the upper and lower group separately. 3. Apply formula Formula D= RU – RL/(n) Example: 10-4/20 = 0.30
- 17. Relationship between difficulty value and discrimination power ● Both are complementary not contradictory to each other. ● Both should be considered in selecting good item. ● If an item has negative discrimination or zero discrimination, it should be rejected whatever the difficulty value is.
- 18. Keep, Revise or Reject When an item meets the general acceptability guidelines for difficulty and discrimination you should keep the item if it falls outside the guidelines. You make a judgement whether to keep, revise or reject it.
- 19. Guidelines for or difficulty level and discrimination index statistics Difficulty level standard range is .25 to .75 Item 1- difficulty, .55; DI, .20 Item 2- difficulty, .50; DI, .40 Item 3- difficulty, .74, DI, .48 keep or reject?
- 20. Differences Group Item Response * A B C D Upper group 1 0 11 3 Lower group 2 0 7 6 Note. * denotes correct response Item difficulty: (11 + 7)/30 = .60p Discrimination Index: (11-7)/15 = .267
- 21. Group Item Response * A B C D Upper group 3 2 15 0 Lower group 12 3 3 2 Note. * denotes correct response 74 students took the test 27% = 20(N) Item difficulty: (15 + 3)/40 = .45p Discrimination Index: (15 - 3)/20 = .60
- 22. Group Item Response * A B C D Upper group 0 0 0 0 Lower group 0 0 15 0 Note. * denotes correct response Item difficulty: (0 + 15)/30 = .50p Discrimination Index: (0 - 15)/15 = -1.0
- 23. Cautions ● Difficulty levels should never be negative. if you get a negative result, recalculate! ● Item discriminations can be negative i.e. more students in the low scoring group can get the item correct then those in the top scoring group. ● The general advice is to reject, revise or completely rewrite items with negative item discrimination.
- 24. Pause think and practice What value do difficulty and discrimination indexes have to your teaching? practice: using results from a test you currently administer, calculate the difficulty and discrimination indexes for all or part of the test what do the results tell you?