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Why-MCQs

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Why-MCQs
Benha Faculty of Medicine
Dermatology & Andrology Department
Undergraduate Exam
January 2007
Time allowed 45 min
MCQ TESTING
Why MCQs?
• Test a wide range of issues
• Not affected by a student's
ability to write
• Fair marking
• Quickly marked by computer
• Computer gives analysis
of questions
• A bank of questions can be
built up
• Can be used for quick revision
Weaknesses
of
MCQ tests
• They do not test synthesis
• Time-consuming
• Student's must select from your
alternatives
• Guessing may result in 20-25%
right answers
• Attention to security
• Questions need to be pre-tested
Anatomy
of an MCQ
Impetigo is caused by:
DISTRACTORS
ANSWER
1-Fungi
2-Parasites
3-Viruses
4-Bacteria
STEM
OPTIONS
Before writing
1- Find who's your
audience
• Tailor the topics and difficulty
of questions to the goals of the
course
• Be sensitive to cultural and
gender issues
2-Test for significant
learning outcomes
• Knowledge
Recalling information
The outermost layer of the epidermis
is the:
1-Malpighian layer
2-Basal layer
3-Horny layer
4-Granular layer
• Comprehension
Understanding the meaning of information
Syphilis in pregnancy can be treated
by the following drugs EXCEPT:
1-Penicillin
2-Tetracyclins
3-Macrolides
4-Cephalosprins
• Application
Solving a problem or making a decision
A diabetic patient with pemphigus
vulgaris should be given:
1-10-20 mg prednisolone/day
2-20 mg triamcinolone/day
3-Cyclophosphamide100-200mg/day
4-Acitratin 25 mg/day
3-Ask questions on
important aspects of
the topic
4-Focus on common
student mistakes
e.g. griseofulvin in tinea
versicolor
5-Do not give away answers
to a previous question with a
later question
6-Inform the examinees
about the source of your
questions
Writing The Stem
1-Determine the point to be
tested
2- Avoid dealing with more than
one problem
• In tinea capitis the best systemic
treatment is: 
• In eczematized tinea capitis the
best systemic treatment is: 
3-Avoid including words that do
not contribute to the basis for
choosing between options
Acne is a troublesome disease.
Some drugs used in its treatment are
dangerous during pregnancy e.g.: 
Which of the following drugs is
contraindicated in pregnant women
with acne: 
4-Include as much information in
the stem and as little in the options
as possible
A condition in which a man is unable
to have an erection firm enough for
intromission and copulatory
movements till ejaculation is
called:
ED is defined as: 
5-Avoid negative questions
e.g. which one is NOT an antifungal?
• If this cannot be avoided, negative
words should be: highlighted or in
bold or in capitals
Which of the following drugs is NOT
used in the treatment of ….
Writing The Options
1- Restrict the use of terms such
as "always" or "never" in options
(they are very rarely true)
2-Three or four well constructed
options are enough. Generally, the
minimal improvement to the exam
due to adding a fifth option is not
worth the effort to construct it
3- Avoid "All of the above"
(one recognized distractor
eliminates it )
These drugs are antiscabitic :
1-Ectomethrine
2-Penicillin
3-Digitalis
4-All of the above
4- “None of the above" is
acceptable if the question is
factual
The pudedal artery is a branch
from:
It is probably desirable if computation
yields the answer
The dose of isotretinoin in a 60 kgm
acne patient is :
5- Vary the location of the answer
on as random a basis as possible.
Students know that for some
examiners the first option is rarely
the answer
6-List the options in a logical order,
e.g. if there are numbers the options
should be arranged in ascending or
descending order
7-Avoid grammatical cues i.e. one or
more distractors don’t follow
grammatically from the stem
A patient with itching that increases by
night, a positive family history and
penile itchy papule:
1-Have scabies
2-Has lichen planus
3-Is atopic
8-Options should be homogeneous
Crusts can be found in:
1-Ecthyma
2-Psoriasis
3-Lichen planus
4-ED
9-Distractors should be equally
plausible to a weak candidate
10-Do not repeat information in all
the options needlessly
Rifampicin in leprosy treatment :
1-Should be given as a 300mg dose
once monthly
2-Should be given as a 600mg dose
once monthly
3-Should be given as a 900mg dose
once monthly
11-Have a colleague with expertise in
the contents of the exam review the
items
Marking
The Optical Mark Reading
Scanner
• Students record their answers on
a machine readable answer sheet
• These sheets are fed through an
Optical Mark Reading Scanner
that turns pencil marks into
useable computer information
• If two or more circles are filled in
on the answer sheet, the question
will be marked 'wrong‘
• Specially written software controls
the test scoring and analysis
Negative(formula)
marking:
To use or not to use?
Marks are subtracted every time an
incorrect option has been selected
Theoretically, negative marking is
intended to discourage guessing
The largest systematic study
comparing right scoring and
negative marking showed that
using right scoring produced
slightly higher scores than
formula scoring
Disadvantages of negative
scoring
• It takes examinees longer
• The directions are more complicated
• It might discourage answering
based on good partial knowledge
• May actually penalise the better
students who might be less likely
to give educated guesses
Questions
Evaluation
Does a question
discriminate well
between examinees?
1-Questions answered correctly
by nearly all examinees are
useless for discriminating among
students
2-Questions answered correctly by
more than 85%of students have
markedly reduced power to
discriminate
3- Distractors that are not chosen
by any examinees should be
replaced
Measuring
Discremination Index
ordering the test scores from lowest to highest
1-Arrange
test scores
from lowest
to highest
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
2-Separate
these scores
into four
equal parts
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
}
Lower
quartile
}
Upperer
quartile
3-Determine Ch and Cl
• Ch : No. of students who answered
this question correctly in the high
performing group
• Cl : No. of students who answered
this question correctly in the low
performing group
4-Calculate Discrimination
Index for each group
Discrimination Index= (Ch - Cl)
Nh or Nl
Nh=No.of students in the high
performing group
Nl=No. of students in the low
performing group
•
•
•
•
The bigger the discrimination
index for a question, the better its
ability to dicriminate among
students:
Excellent: > 0.35
Good: 0.35 - 0.25
Acceptable: 0.25 - 0.15
Deleted: < 0.1
Estimation of
a Question Difficulty
• Easiness=
Total No. of correct answers
No. of students who took the test
• Difficulty = 1 – easiness
Too difficult <0.3
Too easy >0.7
Estimation of test difficulty is useful
because:
• It can help determining passing
score
• It gives experience in writing
exams in the future
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