A hospital reports that more accidents happen on days when more ice cream is sold. The most likely explanation is that
- A. ice cream causes accidents
- B. accidents cause ice cream sales
- C. both rise in hot weather, which is a common cause
- D. the report is fabricated
Explanation
Hot weather increases both outdoor activity, and therefore accidents, and ice cream sales, so the two are linked through a third variable rather than to each other. This is the textbook example of a confounding variable. Neither of the direct causal readings makes sense on inspection.
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