CPH – Certified in Public Health |
CPH – CERTIFIED IN PUBLIC HEALTH | EXAM QUESTIONS AND
CORRECT ANSWERS | COMPREHENSIVE PUBLIC HEALTH
CERTIFICATION 2026/2027
NATIONAL BOARD OF PUBLIC HEALTH EXAMINERS — CERTIFICATION
REVIEW
CERTIFIED IN PUBLIC HEALTH (CPH)
Page 1 of 65
, CPH – Certified in Public Health |
1. During a one-year study, 50 new cases of a disease were identified
among 2,000 people who were disease-free at baseline. What is the
cumulative incidence?
A. 2.5 per 1,000
B. 25 per 1,000
C. 40 per 1,000
D. 50 per 1,000
B. 25 per 1,000
Cumulative incidence is new cases divided by the population at risk: 50 ÷
2,000 = 0.025, or 25 per 1,000.
2. A new drug prolongs survival in patients with a chronic disease but
does not cure it. If incidence remains constant, what will happen to
prevalence?
A. Prevalence will decrease
B. Incidence will fall in proportion to prevalence
C. Prevalence will increase
D. Prevalence will stay the same
C. Prevalence will increase
Prevalence is roughly incidence multiplied by duration; longer survival
without cure lengthens duration, so prevalence rises.
Page 2 of 65
, CPH – Certified in Public Health |
3. A screening test produced 90 true positives, 10 false negatives, 30
false positives and 870 true negatives. What is the sensitivity of the
test?
A. 90%
B. 75%
C. 96.7%
D. 99%
A. 90%
Sensitivity equals true positives divided by all people with the disease: 90
÷ (90 + 10) = 90%.
4. A screening program finds 40 true positives and 160 false positives.
What is the positive predictive value?
A. 25%
B. 40%
C. 80%
D. 20%
D. 20%
PPV is true positives divided by all positive results: 40 ÷ 200 = 20%.
5. A screening test with fixed sensitivity and specificity is moved from a
high-prevalence clinic to the general population. What happens to the
positive predictive value?
A. It is unchanged
B. It increases
C. It decreases
D. It becomes equal to the sensitivity
C. It decreases
PPV depends on prevalence; when disease is rarer, a larger share of
positive results are false positives.
Page 3 of 65
, CPH – Certified in Public Health |
6. In a cohort study, disease incidence was 30 per 1,000 among exposed
persons and 10 per 1,000 among unexposed persons. What is the
relative risk?
A. 2.0
B. 0.33
C. 3.0
D. 20
C. 3.0
Relative risk is incidence in the exposed divided by incidence in the
unexposed: 30 ÷ 10 = 3.0.
7. Using the same cohort (30 per 1,000 exposed; 10 per 1,000
unexposed), what is the attributable risk among the exposed?
A. 10 per 1,000
B. 20 per 1,000
C. 3 per 1,000
D. 40 per 1,000
B. 20 per 1,000
Attributable risk (risk difference) is 30 − 10 = 20 per 1,000, the excess
risk linked to the exposure.
8. In a case-control study, 40 cases and 20 controls were exposed, while
60 cases and 80 controls were unexposed. What is the odds ratio?
A. 2.00
B. 0.38
C. 2.67
D. 1.50
C. 2.67
OR = (a × d) ÷ (b × c) = (40 × 80) ÷ (20 × 60) = 3,200 ÷ 1,200 = 2.67.
Page 4 of 65
CPH – CERTIFIED IN PUBLIC HEALTH | EXAM QUESTIONS AND
CORRECT ANSWERS | COMPREHENSIVE PUBLIC HEALTH
CERTIFICATION 2026/2027
NATIONAL BOARD OF PUBLIC HEALTH EXAMINERS — CERTIFICATION
REVIEW
CERTIFIED IN PUBLIC HEALTH (CPH)
Page 1 of 65
, CPH – Certified in Public Health |
1. During a one-year study, 50 new cases of a disease were identified
among 2,000 people who were disease-free at baseline. What is the
cumulative incidence?
A. 2.5 per 1,000
B. 25 per 1,000
C. 40 per 1,000
D. 50 per 1,000
B. 25 per 1,000
Cumulative incidence is new cases divided by the population at risk: 50 ÷
2,000 = 0.025, or 25 per 1,000.
2. A new drug prolongs survival in patients with a chronic disease but
does not cure it. If incidence remains constant, what will happen to
prevalence?
A. Prevalence will decrease
B. Incidence will fall in proportion to prevalence
C. Prevalence will increase
D. Prevalence will stay the same
C. Prevalence will increase
Prevalence is roughly incidence multiplied by duration; longer survival
without cure lengthens duration, so prevalence rises.
Page 2 of 65
, CPH – Certified in Public Health |
3. A screening test produced 90 true positives, 10 false negatives, 30
false positives and 870 true negatives. What is the sensitivity of the
test?
A. 90%
B. 75%
C. 96.7%
D. 99%
A. 90%
Sensitivity equals true positives divided by all people with the disease: 90
÷ (90 + 10) = 90%.
4. A screening program finds 40 true positives and 160 false positives.
What is the positive predictive value?
A. 25%
B. 40%
C. 80%
D. 20%
D. 20%
PPV is true positives divided by all positive results: 40 ÷ 200 = 20%.
5. A screening test with fixed sensitivity and specificity is moved from a
high-prevalence clinic to the general population. What happens to the
positive predictive value?
A. It is unchanged
B. It increases
C. It decreases
D. It becomes equal to the sensitivity
C. It decreases
PPV depends on prevalence; when disease is rarer, a larger share of
positive results are false positives.
Page 3 of 65
, CPH – Certified in Public Health |
6. In a cohort study, disease incidence was 30 per 1,000 among exposed
persons and 10 per 1,000 among unexposed persons. What is the
relative risk?
A. 2.0
B. 0.33
C. 3.0
D. 20
C. 3.0
Relative risk is incidence in the exposed divided by incidence in the
unexposed: 30 ÷ 10 = 3.0.
7. Using the same cohort (30 per 1,000 exposed; 10 per 1,000
unexposed), what is the attributable risk among the exposed?
A. 10 per 1,000
B. 20 per 1,000
C. 3 per 1,000
D. 40 per 1,000
B. 20 per 1,000
Attributable risk (risk difference) is 30 − 10 = 20 per 1,000, the excess
risk linked to the exposure.
8. In a case-control study, 40 cases and 20 controls were exposed, while
60 cases and 80 controls were unexposed. What is the odds ratio?
A. 2.00
B. 0.38
C. 2.67
D. 1.50
C. 2.67
OR = (a × d) ÷ (b × c) = (40 × 80) ÷ (20 × 60) = 3,200 ÷ 1,200 = 2.67.
Page 4 of 65
