An ecological study across countries shows high average dietary fat intake correlates with higher national breast cancer mortality. An investigator concludes that women who eat more fat are individually at higher risk of breast cancer. This erroneous conclusion illustrates:
- A Selection bias
- B Ecological fallacy ✓
- C Confounding by age
- D Information bias
Correct answer: B. Ecological fallacy
Explanation
The ecological fallacy is drawing an inference about individuals from associations observed only at the group level. Within-country variation can differ completely from between-country averages, so individual-level risk cannot be established from aggregate data alone. Confounding may operate in such data, but the specific logical error described here, applying a group-level association to individuals, is named the ecological fallacy.
Reference: Park's Textbook of Preventive and Social Medicine, 27th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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