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Educational Measurement and Evaluation

Notes Generally, a good distractor is able to attract more ‘Low Marks’ students to select that particular
response or distract ‘Low Marks’ students towards selecting that particular response. What
determines the effectiveness of distractors ? See Figure which shows how 24 students selected the
options A, B, C and D for a particular question. Option B is a less effective distractor because
many ‘High Marks’ students (n = 5) selected option B. Option D is relatively a good distractor
because 2 students from the ‘High Marks’ group and 5 students from the ‘Low Marks’ group
selected this option. The analysis of response options shows that those who missed the item were
about equally likely to choose answer B and answer D. No students chose answer C. Answer C
does not act as a distractor. Students are not choosing between four answer options on this item,
they are really choosing between only three options, as they are not even considering answer C.
This makes guessing correctly more likely, which hurts the validity of the item. The discrimination
index can be improved by modifying and improving options B and C.

Activity
Which British resident was killed by Maharajalela in Pasir Salak ?
H. Low Birch Brooke Gurney
Options A B C D No Response
High Marks (n = 15) 4 7 0 4 0
Low Marks (n = 15) 6 3 2 4 0

The answer is B.
Analyse the effectiveness of the distractors.

10.11 A Practical Approach in Item Analysis

Some teachers may find the techniques discussed earlier as time consuming which cannot be
denied (especially when you have a test consisting of 40 items). However, there is a more
practical approach which may take less time. Imagine that you have administered a 40 item test
to a class of 30 students. Surely, it will take a lot of time to analyse the effectiveness of each item
which may discourage teachers from analysing each item in a test. Diederich (1971) proposed a
method of item analysis which can be conducted by the teacher and the students in his or her
class. The following are the steps :
Step 1 : Arrange the 30 answer sheets from the highest score obtained until the lowest score
obtained.
Step 2 : Select the answer sheet that obtained a middle score. Group all answer sheets above
this score as ‘High Marks’ (mark a ‘H’ on these answer sheets). Group all answer sheets
below this score as ‘Low Marks’ group (mark a ‘L’ on these answer sheets).
Step 3 : Divide the class into two groups (High and Low) and distribute the ‘High’ answer
sheets to the High groups and the Low answer sheet to the Low group. Assign one
student in each group to be the counter.
Step 4 : The teacher than asks the class.
Teacher : “The answer for Question # 1 is ‘C’ and those who got it correct, raise your
hand’.

Counter from ‘H’ group : “Fourteen for group H”
Counter from ‘L’ group : “Eight from group L”

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