Lesson 1: Misleading Graphs

About 30 minutes — Activity-based lesson

What You Will Learn

This lesson covers:

Truncated y-axis: starting the scale at a number other than zero
Unequal bar widths or stretched scales
Missing labels and titles that hide important information
Activity: spot the trick in 5 misleading graphs

Truncated y-axis: starting the scale at a number other than zero

This section covers the key ideas about truncated y-axis: starting the scale at a number other than zero. Discuss with your group or family and explore the concepts together.

Unequal bar widths or stretched scales

This section covers the key ideas about unequal bar widths or stretched scales. Discuss with your group or family and explore the concepts together.

Missing labels and titles that hide important information

This section covers the key ideas about missing labels and titles that hide important information. Discuss with your group or family and explore the concepts together.

Activity: spot the trick in 5 misleading graphs

This section covers the key ideas about activity: spot the trick in 5 misleading graphs. Discuss with your group or family and explore the concepts together.

Check Your Understanding

1. What is a truncated y-axis?

Answer: When a graph starts its number scale at a number other than zero. This makes small differences look huge. A bar going from 90 to 95 looks tiny on a 0-100 scale but massive on a 90-100 scale.

2. How can bar widths mislead?

Answer: If one bar is wider than others, it looks like it represents more data even if the height is the same. All bars should be equal width.

3. Why are missing labels a problem?

Answer: Without labels, you cannot know what the graph actually shows. Someone might use a graph without labels to make you assume something that is not true.

4. How can you protect yourself from misleading graphs?

Answer: Always check: Does the y-axis start at zero? Are the bars equal width? Are there labels and titles? Does the graph match the claim being made?

Key Takeaways

Truncated y-axis: starting the scale at a number other than zero
Unequal bar widths or stretched scales
Missing labels and titles that hide important information
Activity: spot the trick in 5 misleading graphs

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