MBI 361 EXAM 3 PRACTICE QUESTIONS & ANSWERS
What is a case control study characterized by? - Answers :Incidence rates may be
computed directly
Residents of three villages were asked to participate in a survey to identify cholera
carriers. Because several cholera deaths had occurred recently, virtually everyone
present at the time underwent examination. The proportion of residents in each village
who were carriers was computed and compared. What is the proper classification of this
study? - Answers :Cross-sectional study
Which of the following is a case-control study? - Answers :Obtaining histories and other
information from a group of known cases and from a comparison group to determine the
relative
In a study begun in 1965, a group of 3,000 adults in Baltimore were asked about alcohol
consumption. The occurrence of cases of cancer between 1981 and 1995 was studied
in this group. This is an example of: - Answers :A prospective cohort study
In a small pilot study, 12 women with endometrial cancer (cancer of the uterus) and 12
women with no apparent disease were contacted and asked whether they had ever
used estrogen. Each woman with cancer was matched by age, race, weight, and parity
to a woman without disease. What kind of study design is this? - Answers :Case-control
study
The physical examination records of the entire freshman class of 1935 at the University
of Minnesota were examined in 1977 to see if their recorded height and weight at the
time of admission to the university was related to the development of coronary heart
disease (CHD) by 1986. This is an example of: - Answers :A retrospective cohort
In a case-control study, which of the following is true? - Answers :-The proportion of
cases with the exposure is compared with the proportion of controls with the exposure
-The investigator may choose to have multiple comparison group
-Recall bias is a potential problem
In which of the following types of study designs does a subject serve as his own
control? - Answers :Case-crossover study
Ecologic fallacy refers to: - Answers :Ascribing the characteristics of a group to every
individual in that group
A researcher wants to investigate if tea consumption (assessed by a biomarker for tea
metabolism) increases the risk of CHD. He uses a case-control study to answer this
question. CHD is rare in younger people. Which two groups are best to enroll and
compare for this purpose? - Answers :The group of CHD cases and a group of those
who do not develop CHD, matched for age
, Which of the following is a true conclusion concerning matching? - Answers :Matching
on many variables may make it difficult to find an appropriate control
In cohort studies of the role of a suspected factor in the etiology of the disease, it is
essential that: - Answers :The exposed and unexposed groups under study be as
similar as possible with regard to possible confounding factors
Which of the following is not an advantage of a prospective cohort study? - Answers :It
usually costs less than a case-control study
Retrospective cohort studies are characterized by which of the following? - Answers
:The required sample size is smaller than that needed for a prospective cohort study
A major problem resulting from the lack of randomization in a cohort study is: - Answers
:The possibility that a factor that led to the exposure itself, might have caused the
disease
In a cohort study, the advantage of starting by selecting a defined population for study
before any of its members become exposed, rather than starting by selecting exposed
and unexposed individuals, is that: - Answers :A number of exposures can be studied
simultaneously
In 2010, investigators were interested in studying early-adult obesity as a risk factor for
cancer mortality. The investigators obtained physician health reports on students who
attended the University of Glasgow between 1948 and 1968. These reports included
records of the students' heights and weights at the time they attended the university.
The students were then followed through 2010. Mortality information was obtained using
death certificates. This study can best be described as a: - Answers :Retrospective
cohort
From 1983 to 1988, blood samples were obtained from 3,450 HIV-negative men in the
Multicenter Aids Cohort Study (MACS) and stored in a national repository. In 2010 a
researcher was interested in examining the association between levels of inflammation
and HIV infection. Of the 3,450 men, 660 men were identified as HIV-infected cases.
The researcher investigated the association between C-reactive protein (CRP) and HIV
infection among these 660 cases and 660 controls, matched to the cases by age and
ethnicity, who did not become infected with HIV. The researcher used the stored blood
samples to measure the serum level of CRP, a marker of systemic inflammation. The
study initiated in 2010 is an example of a: - Answers :Nested case-control study
The major purpose of random assignment in a clinical trial is to: - Answers :Reduce
selection bias in the allocation of treatment
An advertisement in a medical journal stated that "2,000 subjects with sore throats were
treated with our new medicine. Within 4 days, 94% were asymptomatic". The
What is a case control study characterized by? - Answers :Incidence rates may be
computed directly
Residents of three villages were asked to participate in a survey to identify cholera
carriers. Because several cholera deaths had occurred recently, virtually everyone
present at the time underwent examination. The proportion of residents in each village
who were carriers was computed and compared. What is the proper classification of this
study? - Answers :Cross-sectional study
Which of the following is a case-control study? - Answers :Obtaining histories and other
information from a group of known cases and from a comparison group to determine the
relative
In a study begun in 1965, a group of 3,000 adults in Baltimore were asked about alcohol
consumption. The occurrence of cases of cancer between 1981 and 1995 was studied
in this group. This is an example of: - Answers :A prospective cohort study
In a small pilot study, 12 women with endometrial cancer (cancer of the uterus) and 12
women with no apparent disease were contacted and asked whether they had ever
used estrogen. Each woman with cancer was matched by age, race, weight, and parity
to a woman without disease. What kind of study design is this? - Answers :Case-control
study
The physical examination records of the entire freshman class of 1935 at the University
of Minnesota were examined in 1977 to see if their recorded height and weight at the
time of admission to the university was related to the development of coronary heart
disease (CHD) by 1986. This is an example of: - Answers :A retrospective cohort
In a case-control study, which of the following is true? - Answers :-The proportion of
cases with the exposure is compared with the proportion of controls with the exposure
-The investigator may choose to have multiple comparison group
-Recall bias is a potential problem
In which of the following types of study designs does a subject serve as his own
control? - Answers :Case-crossover study
Ecologic fallacy refers to: - Answers :Ascribing the characteristics of a group to every
individual in that group
A researcher wants to investigate if tea consumption (assessed by a biomarker for tea
metabolism) increases the risk of CHD. He uses a case-control study to answer this
question. CHD is rare in younger people. Which two groups are best to enroll and
compare for this purpose? - Answers :The group of CHD cases and a group of those
who do not develop CHD, matched for age
, Which of the following is a true conclusion concerning matching? - Answers :Matching
on many variables may make it difficult to find an appropriate control
In cohort studies of the role of a suspected factor in the etiology of the disease, it is
essential that: - Answers :The exposed and unexposed groups under study be as
similar as possible with regard to possible confounding factors
Which of the following is not an advantage of a prospective cohort study? - Answers :It
usually costs less than a case-control study
Retrospective cohort studies are characterized by which of the following? - Answers
:The required sample size is smaller than that needed for a prospective cohort study
A major problem resulting from the lack of randomization in a cohort study is: - Answers
:The possibility that a factor that led to the exposure itself, might have caused the
disease
In a cohort study, the advantage of starting by selecting a defined population for study
before any of its members become exposed, rather than starting by selecting exposed
and unexposed individuals, is that: - Answers :A number of exposures can be studied
simultaneously
In 2010, investigators were interested in studying early-adult obesity as a risk factor for
cancer mortality. The investigators obtained physician health reports on students who
attended the University of Glasgow between 1948 and 1968. These reports included
records of the students' heights and weights at the time they attended the university.
The students were then followed through 2010. Mortality information was obtained using
death certificates. This study can best be described as a: - Answers :Retrospective
cohort
From 1983 to 1988, blood samples were obtained from 3,450 HIV-negative men in the
Multicenter Aids Cohort Study (MACS) and stored in a national repository. In 2010 a
researcher was interested in examining the association between levels of inflammation
and HIV infection. Of the 3,450 men, 660 men were identified as HIV-infected cases.
The researcher investigated the association between C-reactive protein (CRP) and HIV
infection among these 660 cases and 660 controls, matched to the cases by age and
ethnicity, who did not become infected with HIV. The researcher used the stored blood
samples to measure the serum level of CRP, a marker of systemic inflammation. The
study initiated in 2010 is an example of a: - Answers :Nested case-control study
The major purpose of random assignment in a clinical trial is to: - Answers :Reduce
selection bias in the allocation of treatment
An advertisement in a medical journal stated that "2,000 subjects with sore throats were
treated with our new medicine. Within 4 days, 94% were asymptomatic". The
