Small Multiples, Underused

Edward Tufte’s defense of small multiples has stayed with me longer than almost anything else I’ve read about visualization.

The idea: instead of one complex chart trying to show many variables at once, show many simple charts showing one variable each, arranged so the eye can compare across panels. Let spatial position do the comparative work.

This is still underused. Most dashboards reach for color coding and legends when they should reach for faceting. A 3×3 grid of line charts, each showing one country, beats a single spaghetti chart with nine colored lines almost every time.

Worth revisiting: The Visual Display of Quantitative Information, chapter 4. Still the clearest treatment of this I know.