NR 503 EPIDEMIOLOGY MIDTERM EXAM –
CHAMBERLAIN COLLEGE OF NURSING ||
2025/2026 COMPLETE QUESTIONS &
CORRECT DETAILED ANSWERS ||
GUARANTEED PASS <UPDATED>
Practice Midterm Questions – Epidemiology (NR503 Style)
Q1. Define epidemiology.
Answer:
Epidemiology is the study of the distribution and determinants of health-related states or
events in specified populations, and the application of this study to control health problems.
Q2. Differentiate between incidence and prevalence.
Answer:
• Incidence: Number of new cases of a disease in a population over a specified period of
time.
• Prevalence: Number of all cases (new + existing) of a disease in a population at a given
time.
Q3. What is the difference between descriptive and analytic epidemiology?
Answer:
• Descriptive epidemiology: Focuses on the who, what, when, and where of health
events (person, place, time).
• Analytic epidemiology: Investigates the how and why (causes, risk factors, associations).
, Q4. What is a cohort study?
Answer:
A cohort study follows a group of individuals (exposed and not exposed) over time to see who
develops the outcome (disease). It is useful for studying incidence and risk factors.
Q5. Explain herd immunity.
Answer:
Herd immunity occurs when a high proportion of a population is immune to a disease (through
vaccination or prior infection), reducing the chance of disease spread—even to those who are
not immune.
Q6. Calculate the attack rate given: 50 people attended a picnic, 20 became ill.
Answer:
Attack rate = (Number ill ÷ Total exposed) × 100
= (20 ÷ 50) × 100 = 40%
Q7. What is the difference between sensitivity and specificity of a test?
Answer:
• Sensitivity: Ability of a test to correctly identify those with the disease (true positives).
• Specificity: Ability of a test to correctly identify those without the disease (true
negatives).
Q8. Define endemic, epidemic, and pandemic.
Answer:
• Endemic: Disease consistently present in a population (e.g., malaria in some regions).
• Epidemic: Sudden increase in cases above the expected level in a population.
• Pandemic: Epidemic that spreads across countries or continents (e.g., COVID-19).
Q9. What is the primary purpose of surveillance in public health?
Answer: To systematically collect, analyze, and interpret health data for planning,
implementing, and evaluating public health practice.
CHAMBERLAIN COLLEGE OF NURSING ||
2025/2026 COMPLETE QUESTIONS &
CORRECT DETAILED ANSWERS ||
GUARANTEED PASS <UPDATED>
Practice Midterm Questions – Epidemiology (NR503 Style)
Q1. Define epidemiology.
Answer:
Epidemiology is the study of the distribution and determinants of health-related states or
events in specified populations, and the application of this study to control health problems.
Q2. Differentiate between incidence and prevalence.
Answer:
• Incidence: Number of new cases of a disease in a population over a specified period of
time.
• Prevalence: Number of all cases (new + existing) of a disease in a population at a given
time.
Q3. What is the difference between descriptive and analytic epidemiology?
Answer:
• Descriptive epidemiology: Focuses on the who, what, when, and where of health
events (person, place, time).
• Analytic epidemiology: Investigates the how and why (causes, risk factors, associations).
, Q4. What is a cohort study?
Answer:
A cohort study follows a group of individuals (exposed and not exposed) over time to see who
develops the outcome (disease). It is useful for studying incidence and risk factors.
Q5. Explain herd immunity.
Answer:
Herd immunity occurs when a high proportion of a population is immune to a disease (through
vaccination or prior infection), reducing the chance of disease spread—even to those who are
not immune.
Q6. Calculate the attack rate given: 50 people attended a picnic, 20 became ill.
Answer:
Attack rate = (Number ill ÷ Total exposed) × 100
= (20 ÷ 50) × 100 = 40%
Q7. What is the difference between sensitivity and specificity of a test?
Answer:
• Sensitivity: Ability of a test to correctly identify those with the disease (true positives).
• Specificity: Ability of a test to correctly identify those without the disease (true
negatives).
Q8. Define endemic, epidemic, and pandemic.
Answer:
• Endemic: Disease consistently present in a population (e.g., malaria in some regions).
• Epidemic: Sudden increase in cases above the expected level in a population.
• Pandemic: Epidemic that spreads across countries or continents (e.g., COVID-19).
Q9. What is the primary purpose of surveillance in public health?
Answer: To systematically collect, analyze, and interpret health data for planning,
implementing, and evaluating public health practice.
