1
NR 503 WEEK 8 FINAL EXAM 2026/2027 | Population
Health & Epidemiology | 100/100 Questions & Answer
Solutions | Graded A | Pass Guaranteed - A+ Graded
SECTION 1: EPIDEMIOLOGIC PRINCIPLES & STUDY DESIGN APPLICATIONS (Q1-15)
Q1. A state health department publishes a report describing the age, sex, and
geographic distribution of influenza cases during the 2024-2025 season. No
comparison groups or hypothesis testing are included. Which branch of
epidemiology is represented?
A. Analytic epidemiology
B. Descriptive epidemiology
C. Experimental epidemiology
D. Clinical epidemiology
B. Descriptive epidemiology [CORRECT]
Rationale: Descriptive epidemiology characterizes disease distribution by person
(age, sex, race), place (geography), and time (seasonality, trends) to generate
hypotheses without testing them. Analytic epidemiology (distractor A) employs
comparison groups and statistical testing to evaluate associations, which is absent in
this report.
Correct Answer: B
Q2. A researcher surveys 2,000 adults to determine the current prevalence of type 2
diabetes in a community. No follow-up is planned. Which study design is being
used?
A. Case-control study
B. Cohort study
,2
C. Cross-sectional study
D. Randomized controlled trial
C. Cross-sectional study [CORRECT]
Rationale: A cross-sectional study measures exposure and outcome simultaneously in
a population at a single point in time, making it ideal for estimating prevalence
without follow-up. Distractor B is incorrect because cohort studies require follow-up
over time to measure incidence, and distractor A is incorrect because case-control
studies start with diseased and non-diseased groups.
Correct Answer: C
Q3. A researcher identifies 150 women with ovarian cancer and 300 women without
ovarian cancer, then interviews all subjects about prior oral contraceptive use. Which
study design is described?
A. Prospective cohort study
B. Retrospective cohort study
C. Case-control study
D. Cross-sectional study
C. Case-control study [CORRECT]
Rationale: This is a case-control study because subjects are selected based on disease
status (cases with ovarian cancer and controls without), and past exposure history is
assessed retrospectively. Distractor A is incorrect because prospective cohorts follow
exposed and unexposed subjects forward in time, and distractor B is incorrect
because retrospective cohorts use historical records of exposure to classify groups.
Correct Answer: C
Q4. A researcher classifies 5,000 smokers and 5,000 non-smokers, then follows them
for 10 years to compare lung cancer incidence. Which study design is described?
,3
A. Case-control study
B. Cross-sectional study
C. Prospective cohort study
D. Ecologic study
C. Prospective cohort study [CORRECT]
Rationale: A prospective cohort study classifies subjects by exposure status (smokers
vs. non-smokers) at baseline and follows them forward in time to measure disease
incidence. This design allows direct calculation of relative risk. Distractor A is
incorrect because case-control studies select by disease status, not exposure status,
and distractor B is incorrect because cross-sectional studies have no follow-up
component.
Correct Answer: C
Q5. A researcher notes that countries with higher per capita chocolate consumption
have higher Nobel laureate rates per capita. However, individual-level data on
chocolate consumption and Nobel prizes are unavailable. What is the primary
limitation of this ecologic study?
A. Selection bias
B. Ecological fallacy
C. Recall bias
D. Confounding by income
B. Ecological fallacy [CORRECT]
Rationale: The ecological fallacy occurs when group-level associations are incorrectly
assumed to apply to individuals; high chocolate consumption at the country level
does not mean Nobel laureates personally consume more chocolate. Distractor A is
incorrect because selection bias refers to systematic differences in study
participation, and distractor C is incorrect because recall bias affects individual-level
retrospective exposure assessment.
Correct Answer: B
, 4
Q6. In a cohort study of 1,000 smokers and 2,000 non-smokers followed for 10 years,
100 smokers and 50 non-smokers developed lung cancer. What is the relative risk?
A. 1.0
B. 2.0
C. 3.0
D. 4.0
D. 4.0 [CORRECT]
Rationale: Relative Risk (RR) = Risk in exposed / Risk in unexposed = (100/1,000) /
(50/2,000) = 0..025 = 4.0. This indicates smokers have 4 times the risk of lung
cancer compared to non-smokers. Distractor B incorrectly divides the absolute risks
without calculating incidence proportions (100/50 = 2), and distractor C confuses the
cumulative incidence calculation.
Correct Answer: D
Q7. A case-control study reports an odds ratio of 3.5 for the association between
NSAID use and gastric ulcer. The disease prevalence in the population is 2%. Which
statement about the odds ratio is correct?
A. The OR is exactly equal to the risk ratio
B. The OR approximates the risk ratio because the disease is common
C. The OR approximates the risk ratio because the disease is rare
D. The OR cannot be calculated from case-control data
C. The OR approximates the risk ratio because the disease is rare [CORRECT]
Rationale: When disease prevalence is <10%, the odds ratio closely approximates the
risk ratio because the rare disease assumption means odds and risks are nearly
equivalent. Distractor B is incorrect because the approximation fails when disease is
common (>10%), and distractor A is incorrect because OR and RR are mathematically
distinct measures that only converge under rare disease conditions.
Correct Answer: C
NR 503 WEEK 8 FINAL EXAM 2026/2027 | Population
Health & Epidemiology | 100/100 Questions & Answer
Solutions | Graded A | Pass Guaranteed - A+ Graded
SECTION 1: EPIDEMIOLOGIC PRINCIPLES & STUDY DESIGN APPLICATIONS (Q1-15)
Q1. A state health department publishes a report describing the age, sex, and
geographic distribution of influenza cases during the 2024-2025 season. No
comparison groups or hypothesis testing are included. Which branch of
epidemiology is represented?
A. Analytic epidemiology
B. Descriptive epidemiology
C. Experimental epidemiology
D. Clinical epidemiology
B. Descriptive epidemiology [CORRECT]
Rationale: Descriptive epidemiology characterizes disease distribution by person
(age, sex, race), place (geography), and time (seasonality, trends) to generate
hypotheses without testing them. Analytic epidemiology (distractor A) employs
comparison groups and statistical testing to evaluate associations, which is absent in
this report.
Correct Answer: B
Q2. A researcher surveys 2,000 adults to determine the current prevalence of type 2
diabetes in a community. No follow-up is planned. Which study design is being
used?
A. Case-control study
B. Cohort study
,2
C. Cross-sectional study
D. Randomized controlled trial
C. Cross-sectional study [CORRECT]
Rationale: A cross-sectional study measures exposure and outcome simultaneously in
a population at a single point in time, making it ideal for estimating prevalence
without follow-up. Distractor B is incorrect because cohort studies require follow-up
over time to measure incidence, and distractor A is incorrect because case-control
studies start with diseased and non-diseased groups.
Correct Answer: C
Q3. A researcher identifies 150 women with ovarian cancer and 300 women without
ovarian cancer, then interviews all subjects about prior oral contraceptive use. Which
study design is described?
A. Prospective cohort study
B. Retrospective cohort study
C. Case-control study
D. Cross-sectional study
C. Case-control study [CORRECT]
Rationale: This is a case-control study because subjects are selected based on disease
status (cases with ovarian cancer and controls without), and past exposure history is
assessed retrospectively. Distractor A is incorrect because prospective cohorts follow
exposed and unexposed subjects forward in time, and distractor B is incorrect
because retrospective cohorts use historical records of exposure to classify groups.
Correct Answer: C
Q4. A researcher classifies 5,000 smokers and 5,000 non-smokers, then follows them
for 10 years to compare lung cancer incidence. Which study design is described?
,3
A. Case-control study
B. Cross-sectional study
C. Prospective cohort study
D. Ecologic study
C. Prospective cohort study [CORRECT]
Rationale: A prospective cohort study classifies subjects by exposure status (smokers
vs. non-smokers) at baseline and follows them forward in time to measure disease
incidence. This design allows direct calculation of relative risk. Distractor A is
incorrect because case-control studies select by disease status, not exposure status,
and distractor B is incorrect because cross-sectional studies have no follow-up
component.
Correct Answer: C
Q5. A researcher notes that countries with higher per capita chocolate consumption
have higher Nobel laureate rates per capita. However, individual-level data on
chocolate consumption and Nobel prizes are unavailable. What is the primary
limitation of this ecologic study?
A. Selection bias
B. Ecological fallacy
C. Recall bias
D. Confounding by income
B. Ecological fallacy [CORRECT]
Rationale: The ecological fallacy occurs when group-level associations are incorrectly
assumed to apply to individuals; high chocolate consumption at the country level
does not mean Nobel laureates personally consume more chocolate. Distractor A is
incorrect because selection bias refers to systematic differences in study
participation, and distractor C is incorrect because recall bias affects individual-level
retrospective exposure assessment.
Correct Answer: B
, 4
Q6. In a cohort study of 1,000 smokers and 2,000 non-smokers followed for 10 years,
100 smokers and 50 non-smokers developed lung cancer. What is the relative risk?
A. 1.0
B. 2.0
C. 3.0
D. 4.0
D. 4.0 [CORRECT]
Rationale: Relative Risk (RR) = Risk in exposed / Risk in unexposed = (100/1,000) /
(50/2,000) = 0..025 = 4.0. This indicates smokers have 4 times the risk of lung
cancer compared to non-smokers. Distractor B incorrectly divides the absolute risks
without calculating incidence proportions (100/50 = 2), and distractor C confuses the
cumulative incidence calculation.
Correct Answer: D
Q7. A case-control study reports an odds ratio of 3.5 for the association between
NSAID use and gastric ulcer. The disease prevalence in the population is 2%. Which
statement about the odds ratio is correct?
A. The OR is exactly equal to the risk ratio
B. The OR approximates the risk ratio because the disease is common
C. The OR approximates the risk ratio because the disease is rare
D. The OR cannot be calculated from case-control data
C. The OR approximates the risk ratio because the disease is rare [CORRECT]
Rationale: When disease prevalence is <10%, the odds ratio closely approximates the
risk ratio because the rare disease assumption means odds and risks are nearly
equivalent. Distractor B is incorrect because the approximation fails when disease is
common (>10%), and distractor A is incorrect because OR and RR are mathematically
distinct measures that only converge under rare disease conditions.
Correct Answer: C
