Scatter plot encodes values as position of points on two quantitative axes. John Herschel plotted orbits; Galton’s 1880s regressions made the form famous.
In reports, ads and assignments it fits correlation, outliers and clusters in two measures. Skip it when one axis is not quantitative, or time is the real story.
Mistakes
- Failure modes 1 — one axis is not quantitative, or time is the real story
- 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 correlation, outliers and clusters in two measures.
- 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.
Scatter plot: honour position of points on two quantitative axes, and switch when one axis is not quantitative, or time is the real story.