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You are planning a case-control study of lung cancer to test the hypothesis that vegetable consumption is protective against lung cancer. Would you match on smoking? Explain your answer.
- A. Yes, because smoking is a known confounder for lung cancer.
- B. No, because matching on smoking will introduce overmatching.
- C. Yes, because smoking correlates with vegetable consumption.
- D. No, because smoking is unrelated to vegetable consumption.
Correct Answer: A
Rationale: Smoking is a strong confounder for lung cancer, and matching on smoking helps ensure comparability between cases and controls, preventing spurious associations.
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In epidemiology, the measure of central location generally preferred for summarizing skewed data such as incubation periods is the:
- A. Mean
- B. Median
- C. Midrange
- D. Mode
Correct Answer: B
Rationale: The median is less affected by outliers and skewed data.
When people migrate within the same country,it is called:
- A. in migration
- B. emigration
- C. outmigration
- D. immigration
Correct Answer: A
Rationale: In-migration refers to movement into a particular area within the same country.
Population doubling time is
- A. Growth rate(GR%)/70
- B. 70/GR%
- C. 60/GR%
- D. GR%/60
Correct Answer: B
Rationale: Population doubling time is calculated using the formula 70/GR%, where GR% is the annual growth rate expressed as a percentage.
What health effects have been studied in relation to this event?
- A. Thyroid cancer, leukemia, psychological trauma.
- B. Improved immune function, enhanced cognition.
- C. Weight loss, increased energy.
- D. Better vision, faster reflexes.
Correct Answer: A
Rationale: Studies have linked Chernobyl radiation exposure to thyroid cancer, leukemia, and mental health impacts.
Identify the type of study design described: Fifteen hundred adult men who worked for Lockheed Aircraft were initially examined in 1951 and were classified by diagnostic criteria for coronary artery disease. Every three years they have been reexamined for new cases of the disease; attack rates in different subgroups have been computed annually.
- A. Cohort study
- B. Case-control study
- C. Cross-sectional study
- D. Ecological study
Correct Answer: A
Rationale: This ongoing follow-up represents a cohort study monitoring disease incidence.