ITEM ANALYSIS By Dr. Arthur Joseph At the end of
Description: ITEM ANALYSIS By Dr. Arthur Joseph At the end of this session, participants will be able to: Calculate difficulty index Calculate discrimination index Analyze test itemsquestions Objectives After you create your assessment items and give
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slide1. ITEM ANALYSIS By
Dr. Arthur Joseph<br>
slide2. At the end of this session, participants will be able to:
Calculate difficulty index
Calculate discrimination index
Analyze test items/questions Objectives<br>
slide3. After you create your assessment items and give your test, you can determine:
Difficulty Index. Whether the items are appropriate -- not too difficult or not too easy
Discrimination Index. Whether the test effectively differentiates between students who do well on the overall test and those who do not Item Analysis<br>
slide4. * Denotes correct answer. This table illustrates how many students selected each answer choice for Questions # 1 & # 2<br>
slide5. Difficulty Index
For Question #1, we can see that A was not a very good distractor -- no one selected that answer.
We can compute the Difficulty Index of question #1 by dividing the number of students who choose the correct answer (24) by the number of total students (30).
D.I. = 24/30 = 0.8 Item Analysis<br>
slide6. Difficulty Index
Question # 1 could be regarded as moderately easy, (80%) of students got it correct (Difficulty Index = 0.8)Â
In contrast, Question #2 is much more difficult
Difficulty Index =12/30 =0 .40 Item Analysis<br>
slide7. Question #2 -- more students selected an incorrect answer (B) than selected the correct answer (A)
This item should be carefully analyzed to ensure that B is an appropriate distractor. Item Analysis<br>
slide8. Difficulty index
Discrimination Index Item Analysis: Group of Students<br>
slide9. Table 1: Results of Ten Questions on a Quiz. .<br>
slide10. "1" indicates the answer was correct
"0" indicates it was incorrect Item Analysis: Group of Students<br>
slide11. Calculation of :
(a) Difficulty Index (b) Discrimination Index
Steps
Arranged student scores from highest to lowest with the highest overall scores at the top
Count the number of students in the upper and lower group who got each item correct. For Question #1, there were 4 students in the top half who got it correct, and 4 students in the bottom half
Determine the Difficulty Index by dividing the number who got it correct by the total number of students. For Question #1, this would be 8/10 or D.I = 0.80 Item Analysis :Group of students (see Table 1)<br>
slide12. Discrimination Index refers to how well an assessment differentiates between high and low scorers.
4. Determine the Discrimination Index by:
subtracting the number of students in the lower group who got the item correct from the number of students in the upper group who got the item correct.Â
Then, divide by the number of students in each group (in this case, there are five in each group). For Question #1, that means you would subtract 4 from 4, and divide by 5, which results in a Discrimination Index of 0.
The answers for Questions # 1 are provided in Table 2. Item Analysis<br>
slide13. Table 2: Answers for Questions 1-3<br>
slide14. Question?
Calculate and interpret the Discrimination Indices for Questions 2 and 3? Calculation of Discrimination Index<br>
slide15. Table 2: Answers for Questions 1-3<br>
slide16. Discrimination Index - interpretation
You should expect that the high-performing students would select the correct answer for each question more often than the low-performing students. Item Analysis<br>
slide17. Discrimination Index--- Interpretation
1. If this is true, then the assessment is said to have a positive discrimination index (between 0 and 1) -- indicating that students who received a high total score chose the correct answer for a specific item more often than the students who had a lower overall score.
2. The higher the discrimination index the higher the reliability of the test item(i.e. the internal consistency).
3. A discrimination index of 0.30 is regarded as the minimal acceptable level. Item Analysis<br>
slide18. Discrimination Index
4. If, however, you find that more of the low-performing students got a specific item correct, then the item has a negative discrimination index (between -1 and 0).
5. Items that all students get right or wrong yield no discrimination.
6. A negative discrimination index indicates that the question penalizes the more knowledgeable students and needs to be revised or rejected. Item Analysis<br>
slide19. Discrimination Index
Now that we have the table filled in, what does it mean?
We see that Question #2 had a difficulty index of .30 (meaning it was quite difficult), and it also had a negative discrimination index of -0.6 (meaning that the low-performing students were more likely to get this item correct).Â
This question should be carefully analyzed, and probably deleted or changed.
Our "best" overall question is Question 3, which had a moderate difficulty level (.60), and discriminated index of (0.8). Item Analysis<br>
slide20. The End Thank You<br>
Dr. Arthur Joseph<br>
slide2. At the end of this session, participants will be able to:
Calculate difficulty index
Calculate discrimination index
Analyze test items/questions Objectives<br>
slide3. After you create your assessment items and give your test, you can determine:
Difficulty Index. Whether the items are appropriate -- not too difficult or not too easy
Discrimination Index. Whether the test effectively differentiates between students who do well on the overall test and those who do not Item Analysis<br>
slide4. * Denotes correct answer. This table illustrates how many students selected each answer choice for Questions # 1 & # 2<br>
slide5. Difficulty Index
For Question #1, we can see that A was not a very good distractor -- no one selected that answer.
We can compute the Difficulty Index of question #1 by dividing the number of students who choose the correct answer (24) by the number of total students (30).
D.I. = 24/30 = 0.8 Item Analysis<br>
slide6. Difficulty Index
Question # 1 could be regarded as moderately easy, (80%) of students got it correct (Difficulty Index = 0.8)Â
In contrast, Question #2 is much more difficult
Difficulty Index =12/30 =0 .40 Item Analysis<br>
slide7. Question #2 -- more students selected an incorrect answer (B) than selected the correct answer (A)
This item should be carefully analyzed to ensure that B is an appropriate distractor. Item Analysis<br>
slide8. Difficulty index
Discrimination Index Item Analysis: Group of Students<br>
slide9. Table 1: Results of Ten Questions on a Quiz. .<br>
slide10. "1" indicates the answer was correct
"0" indicates it was incorrect Item Analysis: Group of Students<br>
slide11. Calculation of :
(a) Difficulty Index (b) Discrimination Index
Steps
Arranged student scores from highest to lowest with the highest overall scores at the top
Count the number of students in the upper and lower group who got each item correct. For Question #1, there were 4 students in the top half who got it correct, and 4 students in the bottom half
Determine the Difficulty Index by dividing the number who got it correct by the total number of students. For Question #1, this would be 8/10 or D.I = 0.80 Item Analysis :Group of students (see Table 1)<br>
slide12. Discrimination Index refers to how well an assessment differentiates between high and low scorers.
4. Determine the Discrimination Index by:
subtracting the number of students in the lower group who got the item correct from the number of students in the upper group who got the item correct.Â
Then, divide by the number of students in each group (in this case, there are five in each group). For Question #1, that means you would subtract 4 from 4, and divide by 5, which results in a Discrimination Index of 0.
The answers for Questions # 1 are provided in Table 2. Item Analysis<br>
slide13. Table 2: Answers for Questions 1-3<br>
slide14. Question?
Calculate and interpret the Discrimination Indices for Questions 2 and 3? Calculation of Discrimination Index<br>
slide15. Table 2: Answers for Questions 1-3<br>
slide16. Discrimination Index - interpretation
You should expect that the high-performing students would select the correct answer for each question more often than the low-performing students. Item Analysis<br>
slide17. Discrimination Index--- Interpretation
1. If this is true, then the assessment is said to have a positive discrimination index (between 0 and 1) -- indicating that students who received a high total score chose the correct answer for a specific item more often than the students who had a lower overall score.
2. The higher the discrimination index the higher the reliability of the test item(i.e. the internal consistency).
3. A discrimination index of 0.30 is regarded as the minimal acceptable level. Item Analysis<br>
slide18. Discrimination Index
4. If, however, you find that more of the low-performing students got a specific item correct, then the item has a negative discrimination index (between -1 and 0).
5. Items that all students get right or wrong yield no discrimination.
6. A negative discrimination index indicates that the question penalizes the more knowledgeable students and needs to be revised or rejected. Item Analysis<br>
slide19. Discrimination Index
Now that we have the table filled in, what does it mean?
We see that Question #2 had a difficulty index of .30 (meaning it was quite difficult), and it also had a negative discrimination index of -0.6 (meaning that the low-performing students were more likely to get this item correct).Â
This question should be carefully analyzed, and probably deleted or changed.
Our "best" overall question is Question 3, which had a moderate difficulty level (.60), and discriminated index of (0.8). Item Analysis<br>
slide20. The End Thank You<br>