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Activity focus

  • misleading graph detection
  • scale and axis interpretation
  • counts vs percentages

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Practice set

  1. State whether each problem is serious:
    • 3D bars
    • truncated y-axis
    • percentages summing to 115%
  2. Explain when percentage comparison is better than raw count comparison.
  3. A graph shows two bars: 50 and 55, but the second bar looks twice as tall.
    • what likely went wrong?

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Answer key

    • 3D bars: can mislead
    • truncated y-axis: can mislead
    • percentages summing to 115%: incorrect if one whole is represented
  2. When group totals differ and we care about relative share.
  3. The scale or bar design is visually distorted.