NR 503 / NR503 Midterm Exam Actual Exam 2026 |
Population Health Epidemiology & Biostatistics |
Questions with Verified Answers | 100% Correct | Pass
Guaranteed
SECTION 1: Epidemiological Concepts & Measures
Q1: In a cohort of 1,000 healthy adults followed for 2 years, 40 new cases of
hypertension are diagnosed. The incidence rate is calculated as:
A. 40/1,000
B. 20/1,000 per year
C. 40/2,000 per year
D. 20/1,000
Correct Answer: B
Rationale: Incidence rate = new cases / total person-time. 40 cases over 2 years in
1,000 adults = 20 cases per year per 1,000 (1,000 × 2 = 2,000 person-years; 40/2,000 =
20/1,000 per year). Option A ignores time; C mislabels denominator; D omits “per year.”
Q2: Which measure best expresses the probability that an individual will develop a
disease during a specified period?
A. Prevalence
B. Incidence
C. Attack rate
, D. Cumulative incidence
Correct Answer: D
Rationale: Cumulative incidence is the proportion of a population at risk that becomes
diseased over a stated time. Incidence (B) is a rate; prevalence (A) is existing cases;
attack rate (C) is used during outbreaks.
Q3: A sudden outbreak of salmonella occurs among 200 banquet attendees; 80 become
ill. The attack rate is:
A. 20 %
B. 40 %
C. 80 %
D. 200 %
Correct Answer: B
Rationale: Attack rate = cases / total exposed = 80/200 = 40 %. Option A halves the
correct value; C uses only cases; D exceeds 100 %.
Q4: When investigators report an age-standardized mortality ratio (SMR) of 1.3, they are:
A. Adjusting for confounding by age using an external standard population.
B. Estimating the crude death rate in the study cohort.
C. Calculating the probability of surviving beyond 65 years.
D. Comparing median ages between exposed and unexposed groups.
Correct Answer: A
Population Health Epidemiology & Biostatistics |
Questions with Verified Answers | 100% Correct | Pass
Guaranteed
SECTION 1: Epidemiological Concepts & Measures
Q1: In a cohort of 1,000 healthy adults followed for 2 years, 40 new cases of
hypertension are diagnosed. The incidence rate is calculated as:
A. 40/1,000
B. 20/1,000 per year
C. 40/2,000 per year
D. 20/1,000
Correct Answer: B
Rationale: Incidence rate = new cases / total person-time. 40 cases over 2 years in
1,000 adults = 20 cases per year per 1,000 (1,000 × 2 = 2,000 person-years; 40/2,000 =
20/1,000 per year). Option A ignores time; C mislabels denominator; D omits “per year.”
Q2: Which measure best expresses the probability that an individual will develop a
disease during a specified period?
A. Prevalence
B. Incidence
C. Attack rate
, D. Cumulative incidence
Correct Answer: D
Rationale: Cumulative incidence is the proportion of a population at risk that becomes
diseased over a stated time. Incidence (B) is a rate; prevalence (A) is existing cases;
attack rate (C) is used during outbreaks.
Q3: A sudden outbreak of salmonella occurs among 200 banquet attendees; 80 become
ill. The attack rate is:
A. 20 %
B. 40 %
C. 80 %
D. 200 %
Correct Answer: B
Rationale: Attack rate = cases / total exposed = 80/200 = 40 %. Option A halves the
correct value; C uses only cases; D exceeds 100 %.
Q4: When investigators report an age-standardized mortality ratio (SMR) of 1.3, they are:
A. Adjusting for confounding by age using an external standard population.
B. Estimating the crude death rate in the study cohort.
C. Calculating the probability of surviving beyond 65 years.
D. Comparing median ages between exposed and unexposed groups.
Correct Answer: A
