# Data Visualization

## Chart Gate

Use a chart only when it reveals a pattern, comparison, trend, distribution, correlation, flow, density, balance, or attribution that text cannot explain as quickly. Require at least 3 comparable data points unless showing a simple 2-part composition.

## Chart Routing

| Relationship | Preferred visual |
|---|---|
| single metric | KPI callout |
| trend | line or sparkline |
| ranking | horizontal bar |
| comparison | grouped bar |
| part-to-whole | stacked bar or small donut |
| correlation | scatter |
| attribution | waterfall |
| flow | funnel or ordered step list |
| density | heatmap |
| hierarchy | treemap |

## Chart Block Anatomy

1. Insight title
2. Context line with range/filter/source
3. Visual
4. Annotation or focal emphasis
5. Source attribution

## Anti-Patterns

- Chart with one number
- Decorative chart with no insight
- Donut with many slices
- Dual-axis chart without explicit rationale
- Color-only meaning
- Missing source attribution
- Fake or stale data that looks real