Composition & Trends
Composition and trend figures are among the most misused in science. Pie charts obscure differences between similar proportions. Line charts imply continuity that may not exist between discrete time points. Stacked bar charts make the middle segments difficult to compare. Licklider applies appropriate-use guards before generating each of these figure types.
When in doubt, use a bar chart instead of a pie chart. A grouped or stacked bar chart displays the same proportional information as a pie chart but allows direct visual comparison of segment sizes. Pie charts are only clearly superior when there are ≤5 categories with clearly different sizes.
Appropriate-Use Guards
- Pie / Donut: blocked for >7 categories or segments where the smallest category < 5% (too small to see)
- Line chart: continuity disclosure required — lines between discrete time points imply that the intermediate values exist
- Stacked bar: accessibility check required — middle segments cannot be directly compared; color palette must be accessible
Figure Types
Pie / Donut Chart
Conditional use: ≤7 categories, values labeled, no similar-size slices. Alternative: stacked bar.
Line Chart (Time Series)
Longitudinal data with within-subject SEM or CI, repeated-measures annotation, and continuity disclosure.
Stacked Bar Chart
Proportional stacked bars with color accessibility check, value labels, and note on middle-segment comparison limitation.