Matching form to content.
FOR CHANGE OVER TIME
A line chart.
Nothing else shows direction as clearly.
FOR COMPARING CATEGORIES
A bar chart.
Horizontal bars, where labels are long.
FOR COMPOSITION
A stacked bar, or a simple table.
FOR RELATIONSHIPS BETWEEN TWO MEASURES
A scatter chart.
FOR A SINGLE IMPORTANT FIGURE
Text. Large, with the comparison beside it.
WHAT NOT TO USE
Pie charts with many segments, which nobody can compare Three-dimensional effects, which distort Dual axes, which mislead
WHY PIE CHARTS FAIL
People compare angles badly. A bar chart answers the same question better.
WHAT TO ASK BEFORE CHARTING
What is the one thing this should show?
Then choose the form that shows it.
WHAT TO AVOID
Charting because a chart is expected.
A table of six numbers is frequently clearer.
WHAT TO TEST
Whether someone unfamiliar reads the intended message immediately.
