MCCQE Population Health and Epidemiology 2

Question 1

A study follows 1,000 smokers and 1,000 non-smokers for 10 years to compare lung cancer incidence. What type of study is this?

Accepted Answer

Prospective cohort study

Answer

Case-control study

Answer

Cross-sectional study

Answer

Randomized controlled trial

Question 2

In a screening program, the positive predictive value of a test is most influenced by which of the following?

Accepted Answer

Prevalence of the disease in the screened population

Answer

Test sensitivity

Answer

Test specificity

Answer

Sample size of the study

Question 3

Which measure of disease frequency accounts for the time each individual is at risk?

Accepted Answer

Incidence rate (person-time)

Answer

Cumulative incidence

Answer

Point prevalence

Answer

Period prevalence

Question 4

A public health intervention reduces the relative risk of stroke from 0.40 to 0.20. What is the relative risk reduction?

Accepted Answer

50%

Answer

20%

Answer

80%

Answer

60%

Question 5

Herd immunity thresholds are primarily determined by which parameter?

Accepted Answer

Basic reproduction number (R₀)

Answer

Case fatality rate

Answer

Incubation period

Answer

Secondary attack rate

Question 6

When comparing two interventions, which statistical measure directly quantifies the clinical importance of a treatment effect rather than just statistical significance?

Accepted Answer

Effect size (e.g., Cohen's d)

Answer

p-value

Answer

95% confidence interval width

Answer

Chi-square statistic

Question 7

A factory worker cohort has higher lung disease rates than the general population. Comparing to the general population introduces which bias?

Accepted Answer

Healthy worker effect

Answer

Recall bias

Answer

Hawthorne effect

Answer

Berkson bias