An ecological study finds that countries with higher per capita chocolate consumption have more Nobel laureates per million population. A newspaper concludes that eating more chocolate increases an individual's chance of winning a Nobel Prize. The error committed in this conclusion is called:

• A Ecological fallacy ✓
• B Berkson's bias
• C Neyman's bias
• D Confounding by indication

Explanation

Ecological fallacy is the mistaken inference from group-level associations to individual-level relationships. An association observed between aggregate variables across populations need not hold at the individual level, because unmeasured group characteristics such as research funding or education systems drive both variables. Berkson's bias arises in hospital-based sampling, Neyman's bias from prevalent survivor cases, and confounding by indication occurs in observational treatment comparisons. All three operate at the individual level, unlike this error.

Reference: Park's Textbook of Preventive and Social Medicine, 27th ed.

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