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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.
Principles
- Encoding — The core mark of Bar chart is length of rectangles on one baseline.
- History — William Playfair, Commercial and Political Atlas, 1786
- Fit — comparing a handful of categories at one time
- Shared baseline — The eye compares length and position more accurately than area.
- Audience — PowerPoint, Excel or Google Sheets and Meta, Google and retail print share the same geometry.
Misconceptions
- Pretty equals true — Decoration rarely persuades; it slows reading.
- 3-D helps — Perspective distortion wrecks comparison. Keep it flat.
- More series is richer — Do not stack stories. One Bar chart, one claim.
- Default palette is fine — Rainbow defaults fail color-blind viewers and grey print. Change Excel or Google Sheets defaults.
Why it matters
- Work — Work: comparing a handful of categories at one time. Readable in four minutes in PowerPoint.
- Ads — Ads: one number and one shape speak first in Meta, Google and retail print.
- School — School: for lab reports and poster boards, pick the form that answers the rubric.
- Craft — Craft: honour length of rectangles on one baseline and decoration falls away.
Bar chart: honour length of rectangles on one baseline, and switch when too many categories, 3-D extrusion, or dual-axis tricks.