NBME CBSE: PUBLIC HEALTH SCIENCES PT. 1 [EXAM
QUESTIONS AND ANSWERS GRADED A] REAL EXAM
EXAM
1. During a high-priority assessment, the practitioner must select the best answer. A
confirmatory test aims to identify people without disease accurately; which property is most
important?
A. high random error
✓ B. high specificity
C. low validity
D. high false-negative rate
Rationale: High specificity minimizes false positives and is useful when confirming a diagnosis or avoiding
unnecessary treatment.
2. During a high-priority assessment, careful prioritization is required. A community
intervention reduces new cases over a year; which epidemiologic measure is most directly
affected?
✓ A. incidence
B. population age alone
C. prevalence only
D. case definition wording
Rationale: Incidence measures new cases occurring during a specified period.
3. During a high-priority assessment, a study randomly assigns participants to treatment
groups; which major advantage does randomization provide?
A. it guarantees no loss to follow-up
B. it proves external validity
C. it eliminates measurement error completely
,✓ D. it helps balance known and unknown confounders between groups
Rationale: Randomization helps distribute confounding factors across groups, improving causal inference.
4. During a high-priority assessment, the practitioner must select the best answer. A researcher
finds that an exposure and disease are associated only because a third variable differs between
groups; what is this called?
A. randomization success
B. herd immunity
C. screening sensitivity
✓ D. confounding
Rationale: A confounder is associated with both exposure and outcome and can distort the observed
association.
5. During a high-priority assessment, careful prioritization is required. A vaccination program
reduces transmission because fewer susceptible people remain; which population effect is
illustrated?
✓ A. herd protection
B. selection bias
C. recall bias
D. lead-time bias
Rationale: High population immunity can reduce transmission and indirectly protect susceptible individuals.
6. During a high-priority assessment, a public health team identifies a disease cluster and wants
to determine whether exposure occurred before illness; which epidemiologic concept is most
relevant?
A. billing status
✓ B. temporality
C. hospital architecture
D. random error only
,Rationale: Temporality means the exposure must occur before the outcome for a causal relationship to be
plausible.
7. During a high-priority assessment, the practitioner must select the best answer. A community
has an unusually high infant mortality rate; which response is most appropriate for public
health?
A. assume every case has the same cause
B. ignore social determinants
✓ C. identify modifiable risk factors and target prevention using population-level data
D. focus only on hospital branding
Rationale: Public health uses population data to identify preventable contributors and design targeted
interventions.
8. During a high-priority assessment, careful prioritization is required. A disease occurs at a
much higher rate among people sharing a particular exposure; which measure directly
compares disease occurrence between exposed and unexposed groups?
✓ A. risk ratio
B. case fatality count alone
C. standard deviation alone
D. median only
Rationale: The risk ratio compares incidence or risk among exposed people with risk among unexposed people.
9. During a high-priority assessment, a screening test is designed to detect nearly all people
who truly have a disease; which property is most important?
A. low prevalence
B. high specificity only
C. high false-negative rate
✓ D. high sensitivity
Rationale: High sensitivity minimizes false negatives and is useful when missing a disease would be harmful.
, 10. During a high-priority assessment, the practitioner must select the best answer. A screening
program detects disease earlier but does not reduce mortality; which bias can make survival
appear longer without improving outcomes?
A. publication bias
B. observer bias only
C. recall bias
✓ D. lead-time bias
Rationale: Lead-time bias makes survival from the time of diagnosis appear longer because diagnosis occurs
earlier, even when death is not delayed.
11. A clinician is reviewing a new case when careful prioritization is required. A screening test
is designed to detect nearly all people who truly have a disease; which property is most
important?
A. high specificity only
B. high false-negative rate
C. low prevalence
✓ D. high sensitivity
Rationale: High sensitivity minimizes false negatives and is useful when missing a disease would be harmful.
12. A clinician is reviewing a new case when a community intervention reduces new cases over
a year; which epidemiologic measure is most directly affected?
A. prevalence only
✓ B. incidence
C. population age alone
D. case definition wording
Rationale: Incidence measures new cases occurring during a specified period.
13. A clinician is reviewing a new case when the practitioner must select the best answer. A
study randomly assigns participants to treatment groups; which major advantage does
randomization provide?
QUESTIONS AND ANSWERS GRADED A] REAL EXAM
EXAM
1. During a high-priority assessment, the practitioner must select the best answer. A
confirmatory test aims to identify people without disease accurately; which property is most
important?
A. high random error
✓ B. high specificity
C. low validity
D. high false-negative rate
Rationale: High specificity minimizes false positives and is useful when confirming a diagnosis or avoiding
unnecessary treatment.
2. During a high-priority assessment, careful prioritization is required. A community
intervention reduces new cases over a year; which epidemiologic measure is most directly
affected?
✓ A. incidence
B. population age alone
C. prevalence only
D. case definition wording
Rationale: Incidence measures new cases occurring during a specified period.
3. During a high-priority assessment, a study randomly assigns participants to treatment
groups; which major advantage does randomization provide?
A. it guarantees no loss to follow-up
B. it proves external validity
C. it eliminates measurement error completely
,✓ D. it helps balance known and unknown confounders between groups
Rationale: Randomization helps distribute confounding factors across groups, improving causal inference.
4. During a high-priority assessment, the practitioner must select the best answer. A researcher
finds that an exposure and disease are associated only because a third variable differs between
groups; what is this called?
A. randomization success
B. herd immunity
C. screening sensitivity
✓ D. confounding
Rationale: A confounder is associated with both exposure and outcome and can distort the observed
association.
5. During a high-priority assessment, careful prioritization is required. A vaccination program
reduces transmission because fewer susceptible people remain; which population effect is
illustrated?
✓ A. herd protection
B. selection bias
C. recall bias
D. lead-time bias
Rationale: High population immunity can reduce transmission and indirectly protect susceptible individuals.
6. During a high-priority assessment, a public health team identifies a disease cluster and wants
to determine whether exposure occurred before illness; which epidemiologic concept is most
relevant?
A. billing status
✓ B. temporality
C. hospital architecture
D. random error only
,Rationale: Temporality means the exposure must occur before the outcome for a causal relationship to be
plausible.
7. During a high-priority assessment, the practitioner must select the best answer. A community
has an unusually high infant mortality rate; which response is most appropriate for public
health?
A. assume every case has the same cause
B. ignore social determinants
✓ C. identify modifiable risk factors and target prevention using population-level data
D. focus only on hospital branding
Rationale: Public health uses population data to identify preventable contributors and design targeted
interventions.
8. During a high-priority assessment, careful prioritization is required. A disease occurs at a
much higher rate among people sharing a particular exposure; which measure directly
compares disease occurrence between exposed and unexposed groups?
✓ A. risk ratio
B. case fatality count alone
C. standard deviation alone
D. median only
Rationale: The risk ratio compares incidence or risk among exposed people with risk among unexposed people.
9. During a high-priority assessment, a screening test is designed to detect nearly all people
who truly have a disease; which property is most important?
A. low prevalence
B. high specificity only
C. high false-negative rate
✓ D. high sensitivity
Rationale: High sensitivity minimizes false negatives and is useful when missing a disease would be harmful.
, 10. During a high-priority assessment, the practitioner must select the best answer. A screening
program detects disease earlier but does not reduce mortality; which bias can make survival
appear longer without improving outcomes?
A. publication bias
B. observer bias only
C. recall bias
✓ D. lead-time bias
Rationale: Lead-time bias makes survival from the time of diagnosis appear longer because diagnosis occurs
earlier, even when death is not delayed.
11. A clinician is reviewing a new case when careful prioritization is required. A screening test
is designed to detect nearly all people who truly have a disease; which property is most
important?
A. high specificity only
B. high false-negative rate
C. low prevalence
✓ D. high sensitivity
Rationale: High sensitivity minimizes false negatives and is useful when missing a disease would be harmful.
12. A clinician is reviewing a new case when a community intervention reduces new cases over
a year; which epidemiologic measure is most directly affected?
A. prevalence only
✓ B. incidence
C. population age alone
D. case definition wording
Rationale: Incidence measures new cases occurring during a specified period.
13. A clinician is reviewing a new case when the practitioner must select the best answer. A
study randomly assigns participants to treatment groups; which major advantage does
randomization provide?
