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Population Health and Epidemiology Flashcards

7 cards from real MCCQE practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.

Read the first 7 Population Health and Epidemiology flashcards as text

  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?

    Answer: Prospective cohort study

    A prospective cohort study follows groups with different exposures forward in time to measure disease incidence.

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

    Answer: Prevalence of the disease in the screened population

    Positive predictive value depends heavily on disease prevalence; a highly specific test still has low PPV in low-prevalence populations.

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

    Answer: Incidence rate (person-time)

    Incidence rate (incidence density) uses person-time denominators to account for variable follow-up periods.

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

    Answer: 50%

    Relative risk reduction = (RR_old − RR_new) / RR_old = (0.40 − 0.20) / 0.40 = 50%.

  5. Herd immunity thresholds are primarily determined by which parameter?

    Answer: Basic reproduction number (R₀)

    The herd immunity threshold is calculated as 1 − 1/R₀; a higher R₀ requires greater population immunity.

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

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

    Effect size measures the magnitude of the treatment difference, independent of sample size and statistical significance.

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

    Answer: Healthy worker effect

    The healthy worker effect occurs because employed populations are generally healthier than the general population, underestimating occupational risks.