SKILL.md
Data Visualization
Chart Selection
| Question | Chart Type |
|---|---|
| How does it change over time? | Line chart |
| How do categories compare? | Bar chart (horizontal for long labels) |
| What's the part-to-whole? | Donut chart (5 categories max) or stacked bar |
| What's the distribution? | Histogram or box plot |
| Is there a correlation? | Scatter plot |
| What's the geographic pattern? | Choropleth or bubble map |
| What's the flow/process? | Sankey or flow diagram |
Design Rules
- Title states the insight, not the data. "Revenue grew 3x" not "Revenue 2023-2025."
- Start Y-axis at zero for bar charts. Line charts can start at non-zero with clear labeling.
- Remove chartjunk: gridlines, borders, 3D effects, decorative elements.
- Color with purpose: highlight the data point that matters, gray the rest.
- Label directly on the chart when possible (not in a separate legend).
- Responsive: Charts must be readable on mobile (simplify, don't just shrink).
Anti-Patterns
- Pie charts with more than 5 slices.
- 3D charts (ever).
- Dual Y-axis (almost always confusing).
- Rainbow color schemes (not accessible, not meaningful).
- Truncated axes that exaggerate differences.