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EPIDEMIOLOGY AND BIOSTATISTICS
|ACTUAL 300Qs&As|GRADED A+
Q1. In a population of 10,000 persons, 200 new cases of a
disease occurred during a 1-year period. What is the cumulative
incidence?
a) 2 per 1,000
b) 20 per 1,000
c) 2%
d) Both b and c
Correct Answer: d) Both b and c
*Rationale: Cumulative incidence = (new cases) / (population at
risk) = 200/10,000 = 0.02 = 2% = 20 per 1,000.*
Q2. A study follows 500 healthy women for 5 years. At baseline,
50 have the disease of interest and are excluded. Over 5 years,
30 new cases occur. Total person-years of follow-up is 2,250.
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What is the incidence rate?
a) 6 per 1,000 person-years
b) 13.3 per 1,000 person-years
c) 30 per 1,000 person-years
d) 60 per 1,000 person-years
Correct Answer: b) 13.3 per 1,000 person-years
*Rationale: Incidence rate = new cases / person-time = 30 /
2,250 = 0.01333 = 13.3 per 1,000 person-years.*
Q3. Which measure of disease frequency is most appropriate
for a rapidly fatal disease with short duration?
a) Point prevalence
b) Period prevalence
c) Incidence rate
d) Cumulative incidence
Correct Answer: c) Incidence rate
Rationale: For short-duration diseases, prevalence approximates
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incidence × duration. Incidence rate (person-time) is preferred
because it accounts for varying follow-up and is less affected by
disease duration.
Q4. In a cross-sectional survey of 1,000 adults, 100 have
hypertension. What is the prevalence of hypertension?
a) 1%
b) 5%
c) 10%
d) 20%
Correct Answer: c) 10%
*Rationale: Prevalence = (existing cases) / (total population) =
100/1,000 = 0.10 = 10%.*
Q5. A cohort study follows 2,000 smokers and 3,000 non-
smokers for 10 years. At the end, there are 200 lung cancer
cases among smokers and 30 among non-smokers. The incidence
rate ratio (relative risk) is approximately:
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a) 0.33
b) 1.5
c) 6.7
d) 10.0
Correct Answer: d) 10.0
*Rationale: Incidence smokers = 200/2,000 = 0.10 = 10%.
Incidence non-smokers = 30/3,000 = 0.01 = 1%. Risk ratio =
0..01 = 10.0.*
Q6. If the incidence of a disease is 5 per 10,000 person-years
and the average duration is 2 years, what is the approximate
prevalence?
a) 1 per 10,000
b) 5 per 10,000
c) 10 per 10,000
d) 25 per 10,000
EPIDEMIOLOGY AND BIOSTATISTICS
|ACTUAL 300Qs&As|GRADED A+
Q1. In a population of 10,000 persons, 200 new cases of a
disease occurred during a 1-year period. What is the cumulative
incidence?
a) 2 per 1,000
b) 20 per 1,000
c) 2%
d) Both b and c
Correct Answer: d) Both b and c
*Rationale: Cumulative incidence = (new cases) / (population at
risk) = 200/10,000 = 0.02 = 2% = 20 per 1,000.*
Q2. A study follows 500 healthy women for 5 years. At baseline,
50 have the disease of interest and are excluded. Over 5 years,
30 new cases occur. Total person-years of follow-up is 2,250.
,Page 2 of 76
What is the incidence rate?
a) 6 per 1,000 person-years
b) 13.3 per 1,000 person-years
c) 30 per 1,000 person-years
d) 60 per 1,000 person-years
Correct Answer: b) 13.3 per 1,000 person-years
*Rationale: Incidence rate = new cases / person-time = 30 /
2,250 = 0.01333 = 13.3 per 1,000 person-years.*
Q3. Which measure of disease frequency is most appropriate
for a rapidly fatal disease with short duration?
a) Point prevalence
b) Period prevalence
c) Incidence rate
d) Cumulative incidence
Correct Answer: c) Incidence rate
Rationale: For short-duration diseases, prevalence approximates
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incidence × duration. Incidence rate (person-time) is preferred
because it accounts for varying follow-up and is less affected by
disease duration.
Q4. In a cross-sectional survey of 1,000 adults, 100 have
hypertension. What is the prevalence of hypertension?
a) 1%
b) 5%
c) 10%
d) 20%
Correct Answer: c) 10%
*Rationale: Prevalence = (existing cases) / (total population) =
100/1,000 = 0.10 = 10%.*
Q5. A cohort study follows 2,000 smokers and 3,000 non-
smokers for 10 years. At the end, there are 200 lung cancer
cases among smokers and 30 among non-smokers. The incidence
rate ratio (relative risk) is approximately:
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a) 0.33
b) 1.5
c) 6.7
d) 10.0
Correct Answer: d) 10.0
*Rationale: Incidence smokers = 200/2,000 = 0.10 = 10%.
Incidence non-smokers = 30/3,000 = 0.01 = 1%. Risk ratio =
0..01 = 10.0.*
Q6. If the incidence of a disease is 5 per 10,000 person-years
and the average duration is 2 years, what is the approximate
prevalence?
a) 1 per 10,000
b) 5 per 10,000
c) 10 per 10,000
d) 25 per 10,000
