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Biostatistics & Research · single question

A study shows that fewer people who exercise got COVID compared to those who don't exercise (300 vs. 650). What does this demonstrate?

  1. This demonstrates a causal relationship between exercise and COVID prevention
  2. Exercise causes COVID immunity
  3. COVID is more common in non-exercisers by coincidence
  4. Less people who exercised got COVID — exercise may be protective
Show answer and explanation

Correct answer: D. Less people who exercised got COVID — exercise may be protective

  • A. Causal relationships require RCT design with randomization; observational studies only show association.
  • B. Saying exercise 'causes immunity' overstates what this study can prove — causation requires controlled experimental design.
  • C. This could theoretically be coincidence (confounding), but the most clinically accurate interpretation is that exercise appears associated with lower COVID risk.
  • D. Correct. The data shows an ASSOCIATION — fewer exercisers got COVID. This is consistent with a protective effect of exercise. However, this type of observational data demonstrates association, not causation.

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