tufte-viz

Ideate and critique data visualizations using Edward Tufte's principles from "The Visual Display of Quantitative Information." Use this skill when: (1) Designing new data visualizations or charts (2)

SKILL.md

GitHub

Tufte Visualization Ideation

Apply Edward Tufte's principles to design clear, honest, high-density data visualizations.

Workflow

For new visualizations:

  1. Clarify the data story

    • What comparisons matter?
    • What's the key insight to communicate?
    • Who's the audience?
  2. Select approach using Tufte principles:

    • High comparison need → Small multiples
    • Dense data → Consider data tables, sparklines
    • Time-series → Line charts with minimal grid
    • Part-to-whole → Avoid pie charts; prefer bar/table
  3. Design with data-ink in mind

    • Start minimal, add only what's necessary
    • Every element must earn its ink
    • Default to grayscale; use color purposefully
  4. Apply the eraser test before shipping

    • For every element (label, tick, gridline, border, annotation): can it be erased without losing information that's not already conveyed elsewhere?
    • Watch for duplicate encodings: numeric labels next to a value already marked by a tick; legends duplicating direct labels; per-panel scale annotations duplicating a shared-scale caption.
    • If two elements compete for the same job, keep the visual one and drop the textual one (or vice versa) — not both.
  5. Apply the collision test before shipping

    • For every text element in the plot (axis labels, point annotations, epoch labels, baseline labels, explanatory notes): mentally draw its bounding box. Does anything else — another text element, a data line, dense markers — live in or cross that box?
    • The eraser test catches redundant elements; the collision test catches crowded ones. Both must pass.
    • Standard fixes: move explanatory prose out of the plot into the figcaption; relocate band/epoch labels to a dedicated strip above the plot; push baseline/reference labels to the outside margin; give each in-plot annotation a leader line so the marker and the text occupy clearly separated space.
    • Watch especially: inverted axes (top of plot is now where extreme values cluster, where annotations also want to go); shared-scale small multiples (labels stacked near zero in every panel); dense scatter (text vanishes into the dot cloud unless explicitly cleared).
  6. Apply the Tufte test (see references/tufte-principles.md)

For critiquing visualizations:

  1. Check graphical integrity

    • Calculate lie factor if proportions seem off
    • Verify baselines and scales
    • Look for 3D distortion
  2. Identify chartjunk

    • Decorative elements
    • Heavy grids
    • Unnecessary 3D effects
    • Moiré patterns
  3. Evaluate data-ink ratio

    • What can be erased?
    • What's redundant?
  4. Suggest improvements with specific before/after recommendations

Key Principles Reference

  • references/tufte-principles.md — core principles from Visual Display of Quantitative Information: lie factor, data-ink, chartjunk, small multiples, integrity.
  • references/analytical-design.md — extensions from Envisioning Information, Visual Explanations, and Beautiful Evidence: the 6 principles of analytical design, sparklines, layering & separation, micro/macro, range-frames, causality, confections. Load when designing dashboards, dense displays, sparklines, or explanatory graphics.

Quick checklist:

  • Lie Factor ≈ 1.0 (no visual distortion)
  • Maximum data-ink ratio
  • Zero chartjunk
  • Clear labeling
  • Answers "compared to what?"
  • Shows causality or mechanism where relevant
  • Multivariate (not over-reduced)
  • Words, numbers, images integrated — not segregated
  • Reveals multiple levels of detail (micro + macro)
  • Layering: primary data dominates, secondary recedes
  • Appropriate data density