©JUSTTRACY EXAM SOLUTIONS
13/11/2024 9:50AM
Epidemiology Modified Exam
Questions And Improved Answers
Experimental - answers✔✔Subjects were children enrolled in a health maintenance
organization. At 2 months, each child was randomly given one of two types of a new vaccine
against rotavirus infection. Parents were called by a nurse two weeks later and asked whether
the children had experienced any of a list of side-effects.
Experimental - answers✔✔A study in which children are randomly assigned to receive either
a newly formulated vaccine or the currently available vaccine, and are followed to monitor
for side effects and effectiveness of each vaccine.
Cohort - answers✔✔The Iowa Women's Health Study, in which researchers enrolled 41,837
women in 1986 and collected exposure and lifestyle information to assess the relationship
between these factors and subsequent occurrence of cancer.
Cohort - answers✔✔Occurrence of cancer was identified between April 1991 and July 2002
for 50,000 troops who served in the first Gulf War (ended April 1991) and 50,000 troops who
served elsewhere during the same period.
Case-control - answers✔✔Persons diagnosed with new-onset Lyme disease were asked how
often they walk through woods, use insect repellant, wear short sleeves and pants, etc. Twice
as many patients without Lyme disease from the same physician's practice were asked the
same questions, and the responses in the two groups were compared.
Cross-sectional - answers✔✔Representative sample of residents were telephoned and asked
how much they exercise each week and whether they currently have (have ever been
diagnosed with) heart disease
Case Control - answers✔✔British investigators conducted a study to compare measles-
mumps-rubella (MMR) vaccine history among 1,294 children with pervasive development
disorder (e.g., autism and Asperger's syndrome) and 4,469 children without such disorders.
(They found no association.) This is an example of which type(s) of study?
, ©JUSTTRACY EXAM SOLUTIONS
13/11/2024 9:50AM
cohort study vs case-control study - answers✔✔Subjects are enrolled or categorized on the
basis of their exposure status in a cohort study but not in a case-control study
key feature of a cross-sectional study - answers✔✔-It usually provides information on
prevalence rather than incidence
-It is more useful for descriptive epidemiology than it is for analytic epidemiology
-It is synonymous with survey
The epidemiologic triad of disease causation refers to - answers✔✔Agent, host and
environment
The hallmark feature of an analytic epidemiologic study - answers✔✔Use of an appropriate
comparison group to estimate counterfactual scenario
Vaccine efficacy measures - answers✔✔The proportionate reduction in disease among
vaccinees.
Confounding - answers✔✔a distortion of the association between an exposure and an
outcome that occurs when the study groups differ with respect to other factors that influence
the outcome.
Confounder - answers✔✔an extraneous variable that wholly or partially accounts for the
observed effect of a risk factor on disease status.. The presence of a confounder can lead to
inaccurate results
Three conditions that must be present for confounding to occur: - answers✔✔1. The
confounding factor must be associated with both the risk factor of interest and the outcome.
2. The confounding factor must be distributed unequally among the groups being compared.
3. A confounder cannot be an intermediary step in the causal pathway from the exposure of
interest to the outcome of interest.
13/11/2024 9:50AM
Epidemiology Modified Exam
Questions And Improved Answers
Experimental - answers✔✔Subjects were children enrolled in a health maintenance
organization. At 2 months, each child was randomly given one of two types of a new vaccine
against rotavirus infection. Parents were called by a nurse two weeks later and asked whether
the children had experienced any of a list of side-effects.
Experimental - answers✔✔A study in which children are randomly assigned to receive either
a newly formulated vaccine or the currently available vaccine, and are followed to monitor
for side effects and effectiveness of each vaccine.
Cohort - answers✔✔The Iowa Women's Health Study, in which researchers enrolled 41,837
women in 1986 and collected exposure and lifestyle information to assess the relationship
between these factors and subsequent occurrence of cancer.
Cohort - answers✔✔Occurrence of cancer was identified between April 1991 and July 2002
for 50,000 troops who served in the first Gulf War (ended April 1991) and 50,000 troops who
served elsewhere during the same period.
Case-control - answers✔✔Persons diagnosed with new-onset Lyme disease were asked how
often they walk through woods, use insect repellant, wear short sleeves and pants, etc. Twice
as many patients without Lyme disease from the same physician's practice were asked the
same questions, and the responses in the two groups were compared.
Cross-sectional - answers✔✔Representative sample of residents were telephoned and asked
how much they exercise each week and whether they currently have (have ever been
diagnosed with) heart disease
Case Control - answers✔✔British investigators conducted a study to compare measles-
mumps-rubella (MMR) vaccine history among 1,294 children with pervasive development
disorder (e.g., autism and Asperger's syndrome) and 4,469 children without such disorders.
(They found no association.) This is an example of which type(s) of study?
, ©JUSTTRACY EXAM SOLUTIONS
13/11/2024 9:50AM
cohort study vs case-control study - answers✔✔Subjects are enrolled or categorized on the
basis of their exposure status in a cohort study but not in a case-control study
key feature of a cross-sectional study - answers✔✔-It usually provides information on
prevalence rather than incidence
-It is more useful for descriptive epidemiology than it is for analytic epidemiology
-It is synonymous with survey
The epidemiologic triad of disease causation refers to - answers✔✔Agent, host and
environment
The hallmark feature of an analytic epidemiologic study - answers✔✔Use of an appropriate
comparison group to estimate counterfactual scenario
Vaccine efficacy measures - answers✔✔The proportionate reduction in disease among
vaccinees.
Confounding - answers✔✔a distortion of the association between an exposure and an
outcome that occurs when the study groups differ with respect to other factors that influence
the outcome.
Confounder - answers✔✔an extraneous variable that wholly or partially accounts for the
observed effect of a risk factor on disease status.. The presence of a confounder can lead to
inaccurate results
Three conditions that must be present for confounding to occur: - answers✔✔1. The
confounding factor must be associated with both the risk factor of interest and the outcome.
2. The confounding factor must be distributed unequally among the groups being compared.
3. A confounder cannot be an intermediary step in the causal pathway from the exposure of
interest to the outcome of interest.
