Two-Variable Data: Models and Scatterplots

SAT Math· difficulty 5/5

Researchers find that countries with more cell phones per capita have higher life expectancy. Which is a plausible explanation NOT supported by causation alone?

  • A

    Life expectancy causes phone ownership.

  • B

    Cell phones directly extend life.

  • C

    Phones are unrelated to life expectancy.

  • D

    Wealthier countries have both more phones and better healthcare.

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Explanation

A confounding variable (national wealth/development) likely drives both — correlation does not imply direct causation.

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