ITEM ANALYSIS -ITEM DIFFICULTY AND DISCRIMINATION INDEX.pptx

Item analysis is a vital process in educational assessment, focusing on evaluating individual test items to gauge their effectiveness in distinguishing between students of varying abilities. Two key metrics examined in item analysis are item difficulty and discrimination index. Item difficulty quantifies how easy or difficult an item is by calculating the proportion of students who answered it correctly out of the total number of students. This metric provides insights into the overall mastery level of students regarding that specific item. On the other hand, the discrimination index measures the item's ability to differentiate between high-performing and low-performing students. It is computed by comparing the proportion of top scorers who answered the item correctly with the proportion of bottom scorers who did so. A high discrimination index indicates that the item effectively discriminates between students of different ability levels, highlighting its value in assessing student performance accurately. Together, these analyses help educators identify and refine test items to improve the reliability and validity of assessments in measuring student learning outcomes.

1. ITEM ANALYSIS: Difficulty Index and Discrimination Index

2. At the end of the lesson, the students will be able to : LEARNING OUTCOMES explain the importance of item analysis in evaluating the quality and effectiveness of test items; solve for the item difficulty and discrimination index; and determine the quality of a test item by its difficulty index and discrimination index .

3. ITEM ANALYSIS -refers to the process of examining the student’s response to each item in the test.

4. Important Characteristics of an Item Item Difficulty Discrimination Index

5. ITEM DIFFICULTY -is defined as the number of students who are able to answer the item correctly divided by the total number of students.

6. Item Difficulty = number of students with correct answer/total number of students Example 1: What is the item difficulty index of an item if 25 students are unable to answer it correctly while 75 answered it correctly? The item difficulty is usually expressed in percentage.

7. Example 2: 25 students answered the item correctly while 75 students did not. What is the difficulty index?

8. A high percentage indicates an easy item/question while a low percentage indicates a difficult item. One problem with this type of difficulty index is that it may not actually indicate that the item is difficult (easy).

9. LEVEL OF DIFFICULTY OF AN ITEM

10. DISCRIMINATION INDEX -is the difference between the proportion of the top scorers who got an item correct and the proportion of the lowest scorers who got the item right.

11. FORMULA: Example: Obtain the index of discrimination of an item of the upper 25% of the class had a difficulty index of 0.60 (i.e. 60% of the upper 25% got the correct answer) while the lower 25% of the class had a difficulty index of 0.20. Index of Discrimination = DU - DL (U - Upper Group; L - Lower Group)

12. Example: Consider a multiple choice type of test of which the following data were obtained: The correct response is B. Compute the difficulty index and index of discrimination.

13. Example: 30 students are divided into two groups: 15 students in the lower group and 15 students in the upper group. In the upper group, there are 12 students who answered the item X correctly whereas in the lower group only 6 students answered item X. What is the discrimination index?

14. INDEX DIFFICULTY Where: RU - number in the upper group who answered the item correctly. RL - number in the lower group who answered the item correctly T - total number who tried the item Note: The smaller the percentage figure the more the difficult the item.

15. INDEX OF ITEM DISCRIMINATING POWER Where: P - percentage who answered the item correctly (index of difficulty) R - number who answered the item correctly T - total number who tried the item 0.00 - 0.20 = Very difficult 0.21 - 0.80 = Moderately difficult 0.81 - 1.00 = Very easy

16. ASSESSMENT TEST I. Get the item difficulty of each item. * denotes correct answer (1 point each)

17. ASSESSMENT TEST II. Solve for the discrimination index. (5 points) 40 students are divided into two groups: 20 students in the lower group and 20 students in the upper group. In the upper group, there are 18 students who answered item Z correctly, whereas in the lower group only 8 students answered item Z. What is the discrimination index?

18. ASSESSMENT TEST III. Essay (5 points) Discuss the importance of item analysis in educational assessment.

19. REFERENCE Navarro, R., Santos, R., & Corpuz, B. (2019). Assessment in Learning 1 (4th ed.). Lorimar Publishing Inc.

20. THANK YOU