, Question 1
A community health nurse is reviewing surveillance data and calculates an
age-adjusted mortality rate for a county. The crude mortality rate is 950 per
100,000, but the age-adjusted rate is 720 per 100,000. Which interpretation is
most accurate?
A. The county has a younger population than the standard population,
artificially inflating the crude rate.
B. The county has an older population than the standard population, so
the crude rate overstates mortality risk.
C. The difference indicates a calculation error because adjusted rates
cannot be lower than crude rates.
D. The age-adjusted rate should be used to compare with other counties,
but the crude rate better reflects actual burden on local resources.
Correct Answer: B - The county has an older population than the
standard population, so the crude rate overstates mortality risk.
RATIONALE
Age adjustment removes the effect of age distribution; a lower
adjusted rate means the county's older population inflates the crude
rate. Option A is incorrect because a younger population would make
crude lower than adjusted. Option C is false-adjusted rates can be
lower. Option D is a common misconception; both rates serve
different purposes, but the question asks for interpretation of the
difference, and B correctly identifies the cause.
Question 2
A public health nurse is evaluating a screening program for a disease with low
prevalence. The test has a sensitivity of 95% and specificity of 90%. Which
statement about the positive predictive value (PPV) is most accurate?
A. PPV will be high because sensitivity is high.
B. PPV will be low because low prevalence increases false positives
relative to true positives.
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, C. PPV is independent of prevalence and depends only on sensitivity and
specificity.
D. PPV will be high because specificity is high.
Correct Answer: B - PPV will be low because low prevalence
increases false positives relative to true positives.
RATIONALE
PPV depends on prevalence; when prevalence is low, even a specific
test yields many false positives, lowering PPV. A and D confuse
sensitivity/specificity with predictive value. C is false-PPV is directly
influenced by prevalence (Bayes' theorem). Only B correctly applies
the relationship.
Question 3
A community health nurse is investigating a cluster of Legionnaires' disease
cases. Which epidemiologic measure is most appropriate to identify the
source?
A. Calculate the attack rate among exposed vs. unexposed groups.
B. Determine the case fatality rate.
C. Calculate the age-adjusted incidence rate.
D. Perform a cross-sectional survey of the entire community.
Correct Answer: A - Calculate the attack rate among exposed vs.
unexposed groups.
RATIONALE
Attack rate compares exposed and unexposed groups to identify a
common source, ideal for outbreak investigation. B measures severity,
not source. C adjusts for age but doesn't pinpoint exposure. D is
inefficient for an acute outbreak; attack rate is the standard measure.
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, Question 4
A nurse is using the MAP-IT framework to address obesity in a community.
Which step should be taken immediately after mobilizing partners?
A. Assess the community's needs and resources.
B. Implement evidence-based interventions.
C. Track progress and outcomes.
D. Develop a goal and objectives.
Correct Answer: A - Assess the community's needs and resources.
RATIONALE
MAP-IT sequence: Mobilize, Assess, Plan, Implement, Track. After
mobilizing partners, the next step is Assess. B, C, and D occur later.
This order ensures interventions are tailored to actual needs.
Question 5
A public health nurse is evaluating the effectiveness of a new vaccine program.
Which study design would provide the strongest evidence for causality?
A. Randomized controlled trial
B. Case-control study
C. Cohort study
D. Ecological study
Correct Answer: A - Randomized controlled trial
RATIONALE
Randomized controlled trials (RCTs) are the gold standard for
establishing causality due to randomization and control. Cohort and
case-control studies are observational and weaker for causality.
Ecological studies are weakest due to group-level data. Thus A is
correct.
Page 4
A community health nurse is reviewing surveillance data and calculates an
age-adjusted mortality rate for a county. The crude mortality rate is 950 per
100,000, but the age-adjusted rate is 720 per 100,000. Which interpretation is
most accurate?
A. The county has a younger population than the standard population,
artificially inflating the crude rate.
B. The county has an older population than the standard population, so
the crude rate overstates mortality risk.
C. The difference indicates a calculation error because adjusted rates
cannot be lower than crude rates.
D. The age-adjusted rate should be used to compare with other counties,
but the crude rate better reflects actual burden on local resources.
Correct Answer: B - The county has an older population than the
standard population, so the crude rate overstates mortality risk.
RATIONALE
Age adjustment removes the effect of age distribution; a lower
adjusted rate means the county's older population inflates the crude
rate. Option A is incorrect because a younger population would make
crude lower than adjusted. Option C is false-adjusted rates can be
lower. Option D is a common misconception; both rates serve
different purposes, but the question asks for interpretation of the
difference, and B correctly identifies the cause.
Question 2
A public health nurse is evaluating a screening program for a disease with low
prevalence. The test has a sensitivity of 95% and specificity of 90%. Which
statement about the positive predictive value (PPV) is most accurate?
A. PPV will be high because sensitivity is high.
B. PPV will be low because low prevalence increases false positives
relative to true positives.
Page 2
, C. PPV is independent of prevalence and depends only on sensitivity and
specificity.
D. PPV will be high because specificity is high.
Correct Answer: B - PPV will be low because low prevalence
increases false positives relative to true positives.
RATIONALE
PPV depends on prevalence; when prevalence is low, even a specific
test yields many false positives, lowering PPV. A and D confuse
sensitivity/specificity with predictive value. C is false-PPV is directly
influenced by prevalence (Bayes' theorem). Only B correctly applies
the relationship.
Question 3
A community health nurse is investigating a cluster of Legionnaires' disease
cases. Which epidemiologic measure is most appropriate to identify the
source?
A. Calculate the attack rate among exposed vs. unexposed groups.
B. Determine the case fatality rate.
C. Calculate the age-adjusted incidence rate.
D. Perform a cross-sectional survey of the entire community.
Correct Answer: A - Calculate the attack rate among exposed vs.
unexposed groups.
RATIONALE
Attack rate compares exposed and unexposed groups to identify a
common source, ideal for outbreak investigation. B measures severity,
not source. C adjusts for age but doesn't pinpoint exposure. D is
inefficient for an acute outbreak; attack rate is the standard measure.
Page 3
, Question 4
A nurse is using the MAP-IT framework to address obesity in a community.
Which step should be taken immediately after mobilizing partners?
A. Assess the community's needs and resources.
B. Implement evidence-based interventions.
C. Track progress and outcomes.
D. Develop a goal and objectives.
Correct Answer: A - Assess the community's needs and resources.
RATIONALE
MAP-IT sequence: Mobilize, Assess, Plan, Implement, Track. After
mobilizing partners, the next step is Assess. B, C, and D occur later.
This order ensures interventions are tailored to actual needs.
Question 5
A public health nurse is evaluating the effectiveness of a new vaccine program.
Which study design would provide the strongest evidence for causality?
A. Randomized controlled trial
B. Case-control study
C. Cohort study
D. Ecological study
Correct Answer: A - Randomized controlled trial
RATIONALE
Randomized controlled trials (RCTs) are the gold standard for
establishing causality due to randomization and control. Cohort and
case-control studies are observational and weaker for causality.
Ecological studies are weakest due to group-level data. Thus A is
correct.
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