2 · Choosing the right chart

A chart is an argument, not decoration. The same numbers can be drawn to look reassuring or alarming — so choosing a chart is a decision with consequences.

This lesson covers the six charts you’ll use 95% of the time. For each one: what it’s good at, and what it hides. You’ll see the same column tell three different stories depending on the bin count, watch a box plot conceal two entirely separate groups of people, and learn to spot the truncated axis — the most common way published charts mislead.

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Checkpoint

• Which chart answers “how do these categories compare?” — and which answers “how is this one variable distributed?”
• Why must a bar chart’s axis start at zero, when a line chart’s often need not?
• What can a histogram show you that a box plot cannot?
• A colleague sends you a chart where one country’s bar is three times another’s. What’s the first thing you check?

Why this matters for EURIDICE

Recognising a truncated axis is a media-literacy skill — squarely inside EURIDICE’s Communication & Media focus. Not using the trick yourself is a professional obligation.

Next: Seeing what’s missing — before charting anything, find out what your data isn’t telling you.