Item analysis and validation

1. HELLOW
EVERYONE
I AM RITO
ANTHONY O.
SULTAN

2. “ Guess the picture? What is you
observation?

3. METI YNALISISA
NDA LAVIDITINO
Guess the words?

4. ITEM ANALYSIS
AND VALIDATION

5. Sultan,Rito Anthony
Oba, Shenna Mae
Daya, Merry Anne

6. Introduction
The teacher normally
prepares a draft of the
test. Such a draft is
subjected to item analysis
and validation to ensure
that the final version of the
test would be useful and
functional.

7. Phases of preparing a test
 Try-out phase
TEST
 Item analysis phase
 Item revision phase

8. Try-out phase
The try-out phase is the initial stage of developing test
items, where questions are tested on a small group of
individuals to identify potential issues.

9. Item Analysis phase
 This phase involves analyzing the performance of each
test item after it has been administered to a larger
group of test-takers.

10. Item Revision phase
 In this phase, based on the results of the item
analysis, items that perform poorly are revised or
replaced to improve the overall quality of the test.

11. Item Analysis
Item analysis is especially valuable
in improving items which will be
used again in later tests, but it can
also be used to eliminate
ambiguous or misleading items in a
single test administration.
Item analysis is a process which examines
student responses to individual test items
(questions) in order to assess the quality of those
items and of the test as a whole.
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.

12. Item Analysis
There are two important characteristics of
an item that will be of interest of the teacher:
 Item Difficulty
 Discrimination Index

13. Item Difficulty or the difficulty of an
item
is defined as the number of students who
are able to answer the item correctly divided
by the total number of students. Thus:
Item difficulty = number of students with the correct answer
Total number of students
The item difficulty is usually expressed
in percentage.

14. Here the total number of students is 100,
hence, the item difficulty index is 75/100 or
75%.
Example: What is the item difficulty index of an
item if 25 students are unable to answer it
correctly while 75 answered it correctly?
Item difficulty = number of students with the correct answer
Total number of students
Item difficulty = 75
100
= 75.00%

15. One problem with this type of difficulty
index is that it may not actually indicate that
the item is difficult or easy. A student who
does not know the subject matter will
naturally be unable to answer the item
correctly even if the question is easy. How
do we decide on the basis of this index
whether the item is too difficult or too easy?

16. Range of
Difficulty Index
Interpretation Action
0-.0.25 Difficult Revise or discard
0.26-0.75 Right Difficult Retain
0.76 – above Easy Revise or discard

17.  Difficult items tend to discriminate between
those who know and those who does not
know the answer.
 Easy items cannot discriminate between
those two groups of students.
 We are therefore interested in deriving a
measure that will tell us whether an item can
discriminate between these two groups of
students. Such a measure is called an index
of discrimination.

18. An easy way to derive such a measure is to
measure how difficult an item is with respect to
those in the upper 25% of the class and how
difficult it is with respect to those in the lower
25% of the class. If the upper 25% of the class
found the item easy yet the lower 25% found it
difficult, then the item can discriminate
properly between these two groups. Thus:

19. Index of discrimination = DU – DL
Example: Obtain the index of
discrimination of an item if 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.
DU = 0.60 while DL = 0.20, thus index
of discrimination = .60 - .20 = .40.

20. Theoretically, the index of discrimination
can range from -1.0 (when DU =0 and DL =
1) to 1.0 (when DU = 1 and DL = 0)
When the index of discrimination is equal
to -1, then this means that all of the lower
25% of the students got the correct answer
while all of the upper 25% got the wrong
answer. In a sense, such an index
discriminates correctly between the two
groups but the item itself is highly
questionable.

21. On the other hand, if the index
discrimination is 1.0, then this means
that all of the lower 25% failed to get the
correct answer while all of the upper
25% got the correct answer. This is a
perfectly discriminating item and is the
ideal item that should be included in the
test. As in the case of index difficulty,
we have the following rule of thumb:

22. Range of
Difficulty Index
Interpretation Action
-1.0 to .50 Can discriminate
but the item is
questionable
Discarded
-.55 to .45 Non-discriminating Revised
.46 to 1.0 Discriminating item Include

23. Example: Consider a multiple item choice
type of test with the ff. data were
obtained:
Item Options
1 A B* C D
0 40 20 20 Total
0 15 5 0 Upper 25%
0 5 10 5 Lower 25%
The correct response is B. Let us compute the difficulty
index and index of discrimination.

24. Difficulty index = no. of students getting the correct answer
Total
= 40
100
= 40%, within of a “good item”
The discrimination index can similarly be computed:
DU = no. of students in upper 25% with correct
response/no. of students in the upper 25%
= 15/20 = .75 or 75%

25. DL = no. of students in lower 75% with correct response/
no. of students in the lower 25%
= 5/20 = 25 or 25%
Discrimination Index = DU - DL = 75 - 25 = .50 or 50%.
Thus, the item also has a "good discriminating power".

26. It is also instructive to note that the
distracter A is not an effective distracter
since this was never selected by the
students. Distracter C and D appear to
have a good appeal as distracters.

27.  In summary, item analysis and validation are
essential for creating fair, reliable, and valid
assessments that accurately measure what
they are intended to assess. These processes
contribute to the improvement of education by
ensuring that assessments align with
educational goals and provide meaningful
insights into student performance.