Quiz: Experimental Studies
Contains 25 multiple-choice and true/false questions.
Is limited to 90 minutes.
Allows 1 attempt.
Is worth 75 points.
Submit this assignment by 11:59 p.m. (ET) on Sunday of Module 4: Week 4.
Attempt History
Attempt Time Score
LATEST Attempt 1 14 minutes 75 out of 75
Correct answers are hidden.
Score for this quiz: 75 out of 75
Question 1
3 / 3 pts
As an epidemiologist you are going to investigate the effect of a drug suspected of causing
malformations in newborn infants when the drug in question is taken by pregnant women during the
course of their pregnancies. As your sample you will use the next 200 single births occurring in a given
hospital. For each birth a medication history will be taken from the new mother and from her doctor; in
addition, you will review medical records to verify use of the drug. [N.B.: These mothers are considered
to have been followed prospectively during the entire course of their pregnancies, because a complete
and accurate record of drug use was maintained during pregnancy.]
The resultant data are:
Forty mothers have taken the suspected drug during their pregnancies. Of these mothers, 35 have
delivered malformed infants. In addition, 10 other infants are born with malfunctions.
The relative risk between exposure to the drug and malformations is:
10
12
14
16
18
Question 2
3 / 3 pts
True or False? Cohort studies preserve the temporality of cause (exposure) happening before the effect
(disease)
True
False
Page: 324
Question 3
3 / 3 pts
As an epidemiologist you are going to investigate the effect of a drug suspected of causing
malformations in newborn infants when the drug in question is taken by pregnant women during the
course of their pregnancies. As your sample you will use the next 200 single births occurring in a given
hospital. For each birth a medication history will be taken from the new mother and from her doctor; in
addition, you will review medical records to verify use of the drug. [N.B.: These mothers are considered
to have been followed prospectively during the entire course of their pregnancies, because a complete
and accurate record of drug use was maintained during pregnancy.]
The resultant data are:
Forty mothers have taken the suspected drug during their pregnancies. Of these mothers, 35 have
delivered malformed infants. In addition, 10 other infants are born with malfunctions.
Suppose that a relative risk of 0.5 has been found. Which interpretation might follow?
The risk of congenital malformations is half as high among users of the drug as among non-users.
The risk of congenital malformations is equal among users and non-users of the drug.
The risk of congenital malformations is twice as high among users of the drug as among non-users of
the drug.
Use of the drug is a protective factor for congenital malformations.
A and D
Question 4
3 / 3 pts
True or False? Exposure-based cohort studies permit investigations of exposures that are uncommon.
True
False
Question 5
3 / 3 pts
Nested case-control studies:
use subjects drawn from a cohort study
provide a degree of control over confounding
reduce the cost of collecting exposure information
all of the above
Page: 357
Question 6
3 / 3 pts
Which of the following individuals helped draw people's attention to the method of cohort analysis?
Snow
Frost
Graunt
Hill
Question 7
3 / 3 pts
A major advantage of cohort studies over case-control studies with respect to the role of a suspected
factor in the etiology of a disease is that:
they take less time and are less costly.
they can utilize a more representative population.
it is easier to obtain controls that are not exposed to the suspected factor.
they permit direct estimation of risk of disease in those exposed to the suspected factor.
they can be done on a double-blind basis.
Question 8
3 / 3 pts
Subjects for an exposure-based cohort study would be selected most appropriately from:
certain occupational groups such as battery workers
the residents of a large U.S. county
male Harvard alumni from 1916 to 1950
all of the above
Question 9
3 / 3 pts
True or False? Relative risk is the ratio of the risk of disease among the exposed to the risk among the
unexposed.
True
False
Question 10
3 / 3 pts
True or False? Survival curves may be used to portray patients' survival in clinical studies.
True
False
Question 11
3 / 3 pts
A five-year prospective cohort study has just been completed. The study was designed to assess the
association between supplemental vitamin A exposure and mortality and morbidity for measles. The RR
for incidence of measles was 0.75 and the RR for measles mortality was 0.5.
Which statement is correct?
A cohort study is not an appropriate study design in this case because the association between one
exposure and two different outcomes is being considered.
One of the problems that this study may have faced is individuals lost to follow-up during the five-year
period.
A cohort study is not a good design to study this association because measles is a very common
disease.
Page: 359
Question 12
3 / 3 pts
As an epidemiologist you are going to investigate the effect of a drug suspected of causing
malformations in newborn infants when the drug in question is taken by pregnant women during the
course of their pregnancies. As your sample you will use the next 200 single births occurring in a given
hospital. For each birth a medication history will be taken from the new mother and from her doctor; in
addition, you will review medical records to verify use of the drug. [N.B.: These mothers are considered
to have been followed prospectively during the entire course of their pregnancies, because a complete
and accurate record of drug use was maintained during pregnancy.]
The resultant data are:
Forty mothers have taken the suspected drug during their pregnancies. Of these mothers, 35 have
delivered malformed infants. In addition, 10 other infants are born with malfunctions.
The number of individuals who both did not take the drug and did not give birth to infants who were
malformed was:
140
150
155
160
170
Question 13
3 / 3 pts
In contrast to observational studies, intervention studies are employed to:
generate knowledge about the etiology and natural history of disease
formulate strategies for prevention
test the efficacy of prevention measures
all of the above
Question 14
3 / 3 pts
True or False? Clinical trials enroll individual subjects and enable randomization of subjects to receive or
not receive the intervention.
True
False
Question 15
3 / 3 pts
Which types of health issues are likely to be addressed in community trials?
Smoking cessation
HIV/AIDS
Healthy eating
All of the above topics
Page: 397
Question 16
3 / 3 pts
True or False? Intervention designs involve only controlled clinical trials.
True
False
Question 17
3 / 3 pts
True or False? A therapeutic trial involves the study of the effectiveness of a substance or program to
prevent disease.
True
False
Question 18
3 / 3 pts
True or False? Randomized controlled trials at the community level are typically used in special situations
where there is a simple intervention.
True
False
Question 19
3 / 3 pts
Surrogate endpoints in clinical trials may include:
subclinical disease
physical measures such as reduction in blood pressure
reduction in symptoms associated with disease
all of the above
Question 20
3 / 3 pts
True or False? The purpose of the washout period is to reinforce the carryover effect.
True
False
Question 21
3 / 3 pts
True or False? Treatment crossover refers to any change of treatment for a patient in a clinical trial that
involves a switch of study treatments.
True
False
Question 22
3 / 3 pts
Identify which of the following six types of study designs most appropriately characterizes the situation
described below.
To test the efficacy of a health education program in reducing the risk of foodborne and waterborne
diseases, the residents of two Peruvian villages were given an intensive health education program. At the
end of two years, the incidence rates of important water-borne and food-borne diseases in these villages
were compared with those in two similar control villages without any education program.
Cross-sectional study
Case-control study
Prospective cohort study
Historical prospective cohort study
Clinical trial
Community trial
Question 23
3 / 3 pts
To assess clinical end points, investigators:
compare rates of disease
compare rates of death
compare rates of recovery
all of the above
Question 24
3 / 3 pts
Controlled clinical trials enable researchers to:
derive knowledge about the origins of a disease
exercise control over who will receive an exposure
more accurately identify cause and effect associations
all of the above
Question 25
3 / 3 pts
A major advantage of community trials is that they are:
able to control delivery of the intervention to many study units
able to estimate directly the realistic impact of behavior change
able to randomize subjects precisely to the study conditions
all of the above
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