NBME CBSE:PUBLIC HEALTH SCIENCES|VERIFIED QUESTIONS AND CORRECT
DETAILED ANSWERS|RATED AND GRADED A+ NEW UPDATE| 2026/2027
What is a case series? - ANSWER✔ Description of clinical findings/symptoms for several patients with
the same diagnosis, treatment, or outcome.
What is a cross-sectional study? - ANSWER✔ Assesses the frequency of disease and risk-related
factors in the present.
What is a case-control study? - ANSWER✔ Retrospectively compares a group of people with a disease
to a group without the disease to determine if odds of prior exposure/risk factor differ.
What is a cohort study? - ANSWER✔ Compares a group of people with a given exposure/risk factor to
a group without exposure to determine if the exposure/risk factor is associated with later development
of disease.
What is a twin concordance study? - ANSWER✔ Compares the frequency with which both
monozygotic twins vs both dizygotic twins develop the same disease to measure heritability and
influence of environmental factors.
What is an adoption study? - ANSWER✔ Compares behavioral traits/genetics in siblings raised by
biological vs adoptive parents to measure heritability and influence of environmental factors.
What is an ecological study? - ANSWER✔ Compares the frequency of disease and risk-related factors
across populations to measure population data (not applicable to individuals).
What is a clinic therapeutic trial? - ANSWER✔ An experimental study involving humans that
compares the benefits of two or more interventions.
What are the criteria for a high-quality clinical trial? - ANSWER✔ Randomized, controlled, and
double-blinded
, What is a crossover clinical trial? - ANSWER✔ Compares the effect of multiple treatments on a
subject
What is the purpose of randomizing the order of treatments in a crossover trial? - ANSWER✔ To
avoid bias
What is a washout period in a crossover trial? - ANSWER✔ A period between treatments to eliminate
any lingering effects
What is the advantage of using a crossover trial? - ANSWER✔ Subjects serve as their own controls
What is the intention-to-treat analysis? - ANSWER✔ Analyzing all subjects according to their original
assigned treatment
What is the purpose of intention-to-treat analysis? - ANSWER✔ To avoid bias from attrition,
crossover, and noncompliance
What is the disadvantage of intention-to-treat analysis? - ANSWER✔ May dilute the true effects of
the intervention
What is the as-treated analysis? - ANSWER✔ Analyzing subjects according to the treatment they
actually received
What is the disadvantage of as-treated analysis? - ANSWER✔ Increases the risk of bias
What is the per-protocol analysis? - ANSWER✔ Excluding subjects who did not complete the
originally assigned treatment
What is the disadvantage of per-protocol analysis? - ANSWER✔ Increases the risk of bias
DETAILED ANSWERS|RATED AND GRADED A+ NEW UPDATE| 2026/2027
What is a case series? - ANSWER✔ Description of clinical findings/symptoms for several patients with
the same diagnosis, treatment, or outcome.
What is a cross-sectional study? - ANSWER✔ Assesses the frequency of disease and risk-related
factors in the present.
What is a case-control study? - ANSWER✔ Retrospectively compares a group of people with a disease
to a group without the disease to determine if odds of prior exposure/risk factor differ.
What is a cohort study? - ANSWER✔ Compares a group of people with a given exposure/risk factor to
a group without exposure to determine if the exposure/risk factor is associated with later development
of disease.
What is a twin concordance study? - ANSWER✔ Compares the frequency with which both
monozygotic twins vs both dizygotic twins develop the same disease to measure heritability and
influence of environmental factors.
What is an adoption study? - ANSWER✔ Compares behavioral traits/genetics in siblings raised by
biological vs adoptive parents to measure heritability and influence of environmental factors.
What is an ecological study? - ANSWER✔ Compares the frequency of disease and risk-related factors
across populations to measure population data (not applicable to individuals).
What is a clinic therapeutic trial? - ANSWER✔ An experimental study involving humans that
compares the benefits of two or more interventions.
What are the criteria for a high-quality clinical trial? - ANSWER✔ Randomized, controlled, and
double-blinded
, What is a crossover clinical trial? - ANSWER✔ Compares the effect of multiple treatments on a
subject
What is the purpose of randomizing the order of treatments in a crossover trial? - ANSWER✔ To
avoid bias
What is a washout period in a crossover trial? - ANSWER✔ A period between treatments to eliminate
any lingering effects
What is the advantage of using a crossover trial? - ANSWER✔ Subjects serve as their own controls
What is the intention-to-treat analysis? - ANSWER✔ Analyzing all subjects according to their original
assigned treatment
What is the purpose of intention-to-treat analysis? - ANSWER✔ To avoid bias from attrition,
crossover, and noncompliance
What is the disadvantage of intention-to-treat analysis? - ANSWER✔ May dilute the true effects of
the intervention
What is the as-treated analysis? - ANSWER✔ Analyzing subjects according to the treatment they
actually received
What is the disadvantage of as-treated analysis? - ANSWER✔ Increases the risk of bias
What is the per-protocol analysis? - ANSWER✔ Excluding subjects who did not complete the
originally assigned treatment
What is the disadvantage of per-protocol analysis? - ANSWER✔ Increases the risk of bias
