Overview
Choropleth maps are one of the most common ways to visualize geographic data. They use color scales to represent values for predefined areas, such as countries, states, or zip codes.
Best Practices
- Use normalized data (e.g., per capita or percentage) rather than raw counts to avoid misleading the viewer (larger areas often have higher counts simply because they are larger).
- Choose an appropriate color scale (sequential or diverging).
- Be aware of the 'Modifiable Areal Unit Problem' (MAUP), where changing boundaries can change the perceived pattern.
Use Cases
- Visualizing election results by county.
- Showing average income by state.