Darker cells mean a higher score for this topic on that metric.
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Quick answers
When should I pick Bar chart?
When the story is: comparing a handful of categories at one time.
When should I avoid Bar chart?
Skip it in cases like: too many categories, 3-D extrusion, or dual-axis tricks.
Who invented or popularised it?
William Playfair, Commercial and Political Atlas, 1786
What does it encode?
length of rectangles on one baseline
Is it OK in ads?
Yes if one claim is visible at a glance in Meta, Google and retail print; otherwise link to a full figure.
Will a teacher accept it?
Yes for lab reports and poster boards if axes, units and a source line are present.
Bar chart encodes values as length of rectangles on one baseline. William Playfair, Commercial and Political Atlas, 1786.
In reports, ads and assignments it fits comparing a handful of categories at one time. Skip it when too many categories, 3-D extrusion, or dual-axis tricks.
Mistakes
- Failure modes 1 — too many categories, 3-D extrusion, or dual-axis tricks
- Failure modes 2 — 3-D pies and perspective bars
- Failure modes 3 — Dual axes that fake a correlation
- Failure modes 4 — Truncated axes that shout a small delta
- Failure modes 5 — Legend only, no direct labels
- Failure modes 6 — Missing source, unit or period
Fixes
- Fixes 1 — Return to comparing a handful of categories at one time.
- Fixes 2 — Flat, one axis, direct labels.
- Fixes 3 — Color-blind-safe palette plus pattern.
- Fixes 4 — Rewrite the title as a claim and add a source line.
Bar chart: honour length of rectangles on one baseline, and switch when too many categories, 3-D extrusion, or dual-axis tricks.