Data Visualization Best Practices

What this best practices guide is

Best practices for charts and data visualizations, checked against the UK Government Analysis Function's chart and colour guidance, WCAG 2.2, and the matplotlib, Plotly and Vega-Lite documentation. It covers choosing the chart, encoding and clutter, color and accessibility, axes and scales, titles and annotation, dashboards and interactive charts, and how to avoid charts that mislead.

It has 7 chapters and 29 practices, each with why it matters, what to do and what to avoid. For analysts, data scientists and developers.

Chapter by chapter

1. Start from the question and choose the chart (4 practices)

The right chart follows from the message and the shape of the data. These practices pick a chart type before any styling happens.

2. Encoding and clutter (4 practices)

Every mark, color and line on a chart should carry information. These practices remove what does not and make what does easy to read.

3. Color and accessibility (5 practices)

Color is powerful and easy to misuse. These practices pick color by data type, meet WCAG contrast rules and make sure no one depends on color alone.

4. Axes and scales (4 practices)

Axes decide how big a difference looks. These practices keep the visual size of a change in proportion to the real one.

5. Titles, annotation and context (4 practices)

A chart without context leaves readers to guess what matters. These practices put the message, the explanation and the source on the chart.

6. Dashboards and interactive charts (4 practices)

Dashboards put many charts in front of busy people. These practices keep them focused, fast and usable by everyone.

7. Avoiding misleading charts (4 practices)

A chart can be built from correct numbers and still leave a false impression. These practices catch the common ways that happens.

How it works on Sefism

The guide reads like a short course: a syllabus, then one chapter per page in a focused reader, with a quiz at the end of each chapter for members. The opening chapters are open to everyone. Adding it to your account uses credits, opens every chapter and keeps your progress.

Every claim is checked against the sources listed on the page (8 cited).