Darker cells mean a higher score for this topic on that metric.
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Last reviewed Sources & creditsMedia creditsMethodology
Quick answers
When should I pick Line chart?
When the story is: trends, seasonality and a few series over time.
When should I avoid Line chart?
Skip it in cases like: unordered categories, or more than about four overlapping series.
Who invented or popularised it?
William Playfair, 1786 — later refined for meteorology and markets
What does it encode?
position of a polyline through ordered time
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.
Line chart encodes values as position of a polyline through ordered time. William Playfair, 1786 — later refined for meteorology and markets.
In reports, ads and assignments it fits trends, seasonality and a few series over time. Skip it when unordered categories, or more than about four overlapping series.
Mistakes
- Failure modes 1 — unordered categories, or more than about four overlapping series
- 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 trends, seasonality and a few series over 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.
Line chart: honour position of a polyline through ordered time, and switch when unordered categories, or more than about four overlapping series.