, Question 1
A county health department reports 240 new cases of a chronic disease over
one year among 12,000 residents. Mid-year population was 11,800, and 600
residents already had the disease at the start of the year. Which incidence
measure is most appropriate and what is its value?
A. Cumulative incidence = ,800 = 20.3 per 1,000
B. Incidence rate = ,000 = 20.0 per 1,000
C. Attack rate = = 400 per 1,000
D. Prevalence = (240 + 600) / 11,800 = 71.2 per 1,000
Correct Answer: A - Cumulative incidence = ,800 = 20.3
per 1,000
RATIONALE
Cumulative incidence uses the population at risk (excluding those
already diseased at baseline), so 240/11,800 is correct. Option B uses
total population including prevalent cases, inflating the denominator
incorrectly. Option C misapplies attack rate (used for outbreaks), and
Option D calculates prevalence, not incidence.
Question 2
Which action by a public health nurse best demonstrates the core public health
function of 'assurance' rather than 'assessment' or 'policy development'?
A. Analyzing vital statistics to identify a rising infant mortality trend
B. Drafting a ordinance to mandate lead screening in rental housing
C. Verifying that all children in a jurisdiction receive required
immunizations through provider audits and outreach
D. Conducting a community health needs assessment survey
Correct Answer: C - Verifying that all children in a jurisdiction
receive required immunizations through provider audits and
outreach
Page 2
, RATIONALE
Assurance ensures that necessary services are available and
competent; auditing immunization delivery and closing gaps
exemplifies this. Assessment (A, D) involves monitoring and
diagnosing community health, while policy development (B) involves
crafting laws and plans.
Question 3
A community health nurse is reviewing a policy that requires reporting of all
positive HIV tests to the health department by name. Which ethical principle is
most directly balanced against the duty to protect public health?
A. Beneficence
B. Autonomy and privacy
C. Justice
D. Veracity
Correct Answer: B - Autonomy and privacy
RATIONALE
Named reporting can infringe on individual privacy and autonomy,
requiring justification by public health benefit. Beneficence and
justice are relevant but not the primary tension; veracity concerns
truth-telling, not confidentiality.
Question 4
In an outbreak investigation, the nurse calculates an attack rate of 65% among
attendees who ate potato salad versus 12% among those who did not. Which
measure best quantifies the strength of association?
A. Attributable risk = 53%
B. Relative risk = 5.4
C. Odds ratio = 0.18
D. Population attributable risk = 12%
Page 3
, Correct Answer: B - Relative risk = 5.4
RATIONALE
Relative risk (risk ratio) = 65/12 = 5.4, indicating attendees were 5.4
times more likely to become ill. Attributable risk (A) measures excess
risk, not strength of association; odds ratio (C) is used in case-control
studies; population attributable risk (D) reflects impact on the
population.
Question 5
A public health nurse is evaluating a new screening test for a low-prevalence
disease. Sensitivity is 95%, specificity is 90%, and prevalence is 1%. What is
the approximate positive predictive value (PPV)?
A. 95%
B. 8.8%
C. 50%
D. 90%
Correct Answer: B - 8.8%
RATIONALE
PPV = (sensitivity × prevalence) / [(sensitivity × prevalence) +
((1specificity) × (1prevalence))] =
(0.95×0.01)/[(0.95×0.01)+(0.10×0.99)] = 0.0095/0.1085 8.8%. High
sensitivity does not ensure high PPV when prevalence is low. Options
A, C, and D confuse sensitivity or specificity with predictive value.
Question 6
Which statement best reflects the concept of 'herd immunity' as applied to a
highly transmissible measles outbreak in a school with 92% vaccination
coverage?
A. The 8% unvaccinated are fully protected because most peers are
immune.
Page 4
A county health department reports 240 new cases of a chronic disease over
one year among 12,000 residents. Mid-year population was 11,800, and 600
residents already had the disease at the start of the year. Which incidence
measure is most appropriate and what is its value?
A. Cumulative incidence = ,800 = 20.3 per 1,000
B. Incidence rate = ,000 = 20.0 per 1,000
C. Attack rate = = 400 per 1,000
D. Prevalence = (240 + 600) / 11,800 = 71.2 per 1,000
Correct Answer: A - Cumulative incidence = ,800 = 20.3
per 1,000
RATIONALE
Cumulative incidence uses the population at risk (excluding those
already diseased at baseline), so 240/11,800 is correct. Option B uses
total population including prevalent cases, inflating the denominator
incorrectly. Option C misapplies attack rate (used for outbreaks), and
Option D calculates prevalence, not incidence.
Question 2
Which action by a public health nurse best demonstrates the core public health
function of 'assurance' rather than 'assessment' or 'policy development'?
A. Analyzing vital statistics to identify a rising infant mortality trend
B. Drafting a ordinance to mandate lead screening in rental housing
C. Verifying that all children in a jurisdiction receive required
immunizations through provider audits and outreach
D. Conducting a community health needs assessment survey
Correct Answer: C - Verifying that all children in a jurisdiction
receive required immunizations through provider audits and
outreach
Page 2
, RATIONALE
Assurance ensures that necessary services are available and
competent; auditing immunization delivery and closing gaps
exemplifies this. Assessment (A, D) involves monitoring and
diagnosing community health, while policy development (B) involves
crafting laws and plans.
Question 3
A community health nurse is reviewing a policy that requires reporting of all
positive HIV tests to the health department by name. Which ethical principle is
most directly balanced against the duty to protect public health?
A. Beneficence
B. Autonomy and privacy
C. Justice
D. Veracity
Correct Answer: B - Autonomy and privacy
RATIONALE
Named reporting can infringe on individual privacy and autonomy,
requiring justification by public health benefit. Beneficence and
justice are relevant but not the primary tension; veracity concerns
truth-telling, not confidentiality.
Question 4
In an outbreak investigation, the nurse calculates an attack rate of 65% among
attendees who ate potato salad versus 12% among those who did not. Which
measure best quantifies the strength of association?
A. Attributable risk = 53%
B. Relative risk = 5.4
C. Odds ratio = 0.18
D. Population attributable risk = 12%
Page 3
, Correct Answer: B - Relative risk = 5.4
RATIONALE
Relative risk (risk ratio) = 65/12 = 5.4, indicating attendees were 5.4
times more likely to become ill. Attributable risk (A) measures excess
risk, not strength of association; odds ratio (C) is used in case-control
studies; population attributable risk (D) reflects impact on the
population.
Question 5
A public health nurse is evaluating a new screening test for a low-prevalence
disease. Sensitivity is 95%, specificity is 90%, and prevalence is 1%. What is
the approximate positive predictive value (PPV)?
A. 95%
B. 8.8%
C. 50%
D. 90%
Correct Answer: B - 8.8%
RATIONALE
PPV = (sensitivity × prevalence) / [(sensitivity × prevalence) +
((1specificity) × (1prevalence))] =
(0.95×0.01)/[(0.95×0.01)+(0.10×0.99)] = 0.0095/0.1085 8.8%. High
sensitivity does not ensure high PPV when prevalence is low. Options
A, C, and D confuse sensitivity or specificity with predictive value.
Question 6
Which statement best reflects the concept of 'herd immunity' as applied to a
highly transmissible measles outbreak in a school with 92% vaccination
coverage?
A. The 8% unvaccinated are fully protected because most peers are
immune.
Page 4
