MPH 6011 Final UPDATED Exam
Questions and CORRECT Answers
True or false: A retrospective cohort study is an observational study but a prospective cohort
study is an intervention study. - Correct Answer- False
What study designs are both analytic, observational studies? - Correct Answer- Retrospective
and prospective cohort studies
What is the measure of association if we start with a cohort free of disease and analysis is by
cumulative incidence? - Correct Answer- relative risk
What is the ratio of cumulative incidence rate in exposed compared to cumulative incidence
rate in the unexposed? - Correct Answer- relative risk
What is the measure of association if we start with a cohort free of disease and analysis is by
incidence rates with person-time in the denominator? - Correct Answer- rate ratio
In a cohort study, several design and implementation problems can impact the strength of the
measure of association. Choose which of these problems below is least likely in a cohort
study?
a. information bias
b. absence of temporality
c. loss to follow-up
d. none of the above - Correct Answer- b
Among the items listed below, which design feature or bias is NOT similarly found in both
case-control and cohort studies?
a. both make comparisons between exposed and unexposed groups
b. confounding
, c. both measure exposure before disease occurs
d. both can have misclassification of exposure - Correct Answer- c
Exposure is measured __________ disease occurrence in cohort studies.
a. before
b. after - Correct Answer- a
In a cohort study, the association between smoking and coronary heart disease was
investigated by selecting for study a group of 3000 smokers and 5000 non-smokers who were
free of disease at baseline. Both groups were followed for the development of coronary heart
disease. 84 smokers developed coronary heart disease and 87 non smokers did too. 4913
persons did not develop disease and did not smoke. The measure of association relating
exposed to unexposed would be: - Correct Answer- (84/3000)/(87/5000)
True or false: Attributable risk tells us how much disease can be prevented if exposure is
removed from the population. - Correct Answer- True
In a 20 year cohort study with 30 cases of heart disease in exposed group and 54,308 person
years, while the unexposed group had 60 cases and 51,477 person-years. The measure of
association showed 0.47. The best interpretation of this finding was:
a. exposed group had a greater risk of heart disease than unexposed group
b. unexposed group had reduced risk of heart disease compared to exposed group
c. exposed group had a reduced risk of heart disease compared to the unexposed group -
Correct Answer- c
Which of the following is an advantage of cohort studies?
a. can examine multiple outcomes from a single exposure
b. can match on confounders
c. can avoid recall bias
d. can enroll cases at beginning of study - Correct Answer- a
Questions and CORRECT Answers
True or false: A retrospective cohort study is an observational study but a prospective cohort
study is an intervention study. - Correct Answer- False
What study designs are both analytic, observational studies? - Correct Answer- Retrospective
and prospective cohort studies
What is the measure of association if we start with a cohort free of disease and analysis is by
cumulative incidence? - Correct Answer- relative risk
What is the ratio of cumulative incidence rate in exposed compared to cumulative incidence
rate in the unexposed? - Correct Answer- relative risk
What is the measure of association if we start with a cohort free of disease and analysis is by
incidence rates with person-time in the denominator? - Correct Answer- rate ratio
In a cohort study, several design and implementation problems can impact the strength of the
measure of association. Choose which of these problems below is least likely in a cohort
study?
a. information bias
b. absence of temporality
c. loss to follow-up
d. none of the above - Correct Answer- b
Among the items listed below, which design feature or bias is NOT similarly found in both
case-control and cohort studies?
a. both make comparisons between exposed and unexposed groups
b. confounding
, c. both measure exposure before disease occurs
d. both can have misclassification of exposure - Correct Answer- c
Exposure is measured __________ disease occurrence in cohort studies.
a. before
b. after - Correct Answer- a
In a cohort study, the association between smoking and coronary heart disease was
investigated by selecting for study a group of 3000 smokers and 5000 non-smokers who were
free of disease at baseline. Both groups were followed for the development of coronary heart
disease. 84 smokers developed coronary heart disease and 87 non smokers did too. 4913
persons did not develop disease and did not smoke. The measure of association relating
exposed to unexposed would be: - Correct Answer- (84/3000)/(87/5000)
True or false: Attributable risk tells us how much disease can be prevented if exposure is
removed from the population. - Correct Answer- True
In a 20 year cohort study with 30 cases of heart disease in exposed group and 54,308 person
years, while the unexposed group had 60 cases and 51,477 person-years. The measure of
association showed 0.47. The best interpretation of this finding was:
a. exposed group had a greater risk of heart disease than unexposed group
b. unexposed group had reduced risk of heart disease compared to exposed group
c. exposed group had a reduced risk of heart disease compared to the unexposed group -
Correct Answer- c
Which of the following is an advantage of cohort studies?
a. can examine multiple outcomes from a single exposure
b. can match on confounders
c. can avoid recall bias
d. can enroll cases at beginning of study - Correct Answer- a
