Timeline encodes values as position along an ordered time axis. Joseph Priestley’s 1765 Chart of Biography inspired later atlases.
In reports, ads and assignments it fits ordered events, eras, project milestones. Skip it when you need quantities changing, not just dates.
Mistakes
- Failure modes 1 — you need quantities changing, not just dates
- 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 ordered events, eras, project milestones.
- 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.
Timeline: honour position along an ordered time axis, and switch when you need quantities changing, not just dates.