About
Cleveland and McGill studied what people are able to decode most accurately and defined and ranked visual primitives in the following list.
- Position along a common scale e.g. scatter plot
- Position on identical but nonaligned scales e.g. multiple scatter plots
- Length e.g. bar chart
- Angle & Slope (tie) e.g. pie chart
- Area e.g. bubbles
- Volume, density, and color saturation (tie) e.g. heatmap
- Color hue e.g. newsmap
The ordering does not result in a precise prescription for displaying data but rather is a framework within which to work.