NEWEST CERTIFIED IN PUBLIC HEALTH (CPH)
CERTIFICATION EXAM OFFERED BY NATIONAL
BOARD OF PUBLIC HEALTH EXAMINERS |
COMPLETE EXAM Q&A WITH RATIONALES
1. A screening test for a disease has 95% sensitivity
and 90% specificity. The disease prevalence in the
population is 10%. What is the positive predictive
value (PPV) of the test?**
A) 51%
B) 68%
C) 86%
D) 95%
Correct answer: A
Rationale: PPV = sensitivity × prevalence / [sensitivity
× prevalence + (1−specificity) × (1−prevalence)] =
(0.95×0.10)/[0.95×0.10 + 0.10×0.90] =
0.095/(0.095+0.09) = 0.095/0.185 ≈ 0.514, or 51.4%.
**2. A study follows 5,000 healthy adults for 10 years
and records who develops cardiovascular disease.
This type of study design is best described as:**
,A) Cross-sectional study
B) Case-control study
C) Retrospective cohort study
D) Prospective cohort study
Correct answer: D
Rationale: In a prospective cohort study, participants
are enrolled based on exposure status and followed
forward in time to track the development of
outcomes.
**3. Which measure of central tendency is most
appropriate for a highly skewed distribution, such as
income or hospital length of stay?**
A) Mean
B) Median
C) Mode
D) Range
Correct answer: B
Rationale: The median is resistant to extreme values
and better represents the center of a skewed
distribution.
,**4. A public health department is planning a smoking
cessation program. Which level of prevention is being
implemented?**
A) Primary prevention
B) Secondary prevention
C) Tertiary prevention
D) Quaternary prevention
Correct answer: A
Rationale: Smoking cessation programs prevent the
onset of smoking-related diseases by intervening
before disease occurs, which is primary prevention.
**5. An outbreak of gastrointestinal illness occurs
among passengers on a cruise ship. The attack rate
among those who ate the seafood salad is 80%, while
the attack rate among those who did not is 20%. What
is the relative risk (RR) of illness associated with
eating the seafood salad?**
A) 1.0
B) 2.0
C) 4.0
, D) 6.0
Correct answer: C
Rationale: RR = incidence in exposed / incidence in
unexposed = 80% / 20% = 4.0.
**6. A vaccine is administered to prevent infection.
This intervention operates at which level of the public
health pyramid?**
A) Direct health care services
B) Enabling services
C) Population-based services
D) Infrastructure
Correct answer: C
Rationale: Vaccination programs target entire
populations and are classified as population-based
services, which are the broadest level of the public
health pyramid.
**7. A clinical trial reports a p-value of 0.03 for the
difference in outcomes between treatment and
placebo groups. What is the correct interpretation?**
CERTIFICATION EXAM OFFERED BY NATIONAL
BOARD OF PUBLIC HEALTH EXAMINERS |
COMPLETE EXAM Q&A WITH RATIONALES
1. A screening test for a disease has 95% sensitivity
and 90% specificity. The disease prevalence in the
population is 10%. What is the positive predictive
value (PPV) of the test?**
A) 51%
B) 68%
C) 86%
D) 95%
Correct answer: A
Rationale: PPV = sensitivity × prevalence / [sensitivity
× prevalence + (1−specificity) × (1−prevalence)] =
(0.95×0.10)/[0.95×0.10 + 0.10×0.90] =
0.095/(0.095+0.09) = 0.095/0.185 ≈ 0.514, or 51.4%.
**2. A study follows 5,000 healthy adults for 10 years
and records who develops cardiovascular disease.
This type of study design is best described as:**
,A) Cross-sectional study
B) Case-control study
C) Retrospective cohort study
D) Prospective cohort study
Correct answer: D
Rationale: In a prospective cohort study, participants
are enrolled based on exposure status and followed
forward in time to track the development of
outcomes.
**3. Which measure of central tendency is most
appropriate for a highly skewed distribution, such as
income or hospital length of stay?**
A) Mean
B) Median
C) Mode
D) Range
Correct answer: B
Rationale: The median is resistant to extreme values
and better represents the center of a skewed
distribution.
,**4. A public health department is planning a smoking
cessation program. Which level of prevention is being
implemented?**
A) Primary prevention
B) Secondary prevention
C) Tertiary prevention
D) Quaternary prevention
Correct answer: A
Rationale: Smoking cessation programs prevent the
onset of smoking-related diseases by intervening
before disease occurs, which is primary prevention.
**5. An outbreak of gastrointestinal illness occurs
among passengers on a cruise ship. The attack rate
among those who ate the seafood salad is 80%, while
the attack rate among those who did not is 20%. What
is the relative risk (RR) of illness associated with
eating the seafood salad?**
A) 1.0
B) 2.0
C) 4.0
, D) 6.0
Correct answer: C
Rationale: RR = incidence in exposed / incidence in
unexposed = 80% / 20% = 4.0.
**6. A vaccine is administered to prevent infection.
This intervention operates at which level of the public
health pyramid?**
A) Direct health care services
B) Enabling services
C) Population-based services
D) Infrastructure
Correct answer: C
Rationale: Vaccination programs target entire
populations and are classified as population-based
services, which are the broadest level of the public
health pyramid.
**7. A clinical trial reports a p-value of 0.03 for the
difference in outcomes between treatment and
placebo groups. What is the correct interpretation?**
