Direct answer
Make a chart accessible by pairing every visual encoding with a non-visual equivalent: a colorblind-safe, high-contrast palette plus redundant encoding (pattern, position, or direct labels) for anyone who can't distinguish the colors, and a structured, readable alternative (a data table or text summary) plus keyboard navigation for anyone using a screen reader.
Structured elaboration
- Choropleth map: color alone should never be the only way to read the value; add a legend with explicit numeric bins, and provide an accessible data table (region -> value) as an alternative view, since a screen reader cannot interpret map shading or a keyboard user cannot easily probe a map's regions.
- Stacked bar chart: use a colorblind-safe categorical palette (avoiding red-green as the sole distinguishing pair) plus direct labels or hatch patterns for the segments; provide an accessible table with the same category-by-value breakdown, and ensure each bar segment is keyboard-focusable with a text description ("Region A, Channel 1: $40K").
- Interactive network diagram: the hardest case; provide a structured textual summary of the key relationships ("Node A connects to 5 nodes, most strongly to Node B") and an accessible adjacency table, since a screen reader cannot meaningfully narrate a force-directed layout (a network-diagram arrangement where connected nodes are pulled together and unconnected ones pushed apart like magnets, so the same data can settle into a different-looking arrangement each time it's drawn).
- General WCAG practice: verify contrast ratios (4.5:1 minimum for text, higher for small elements), ensure every interactive element (filter, tooltip trigger) is reachable and operable via keyboard alone, and validate with an automated contrast/ARIA checker (ARIA: markup attributes that tell a screen reader what an interactive element is and how to use it, e.g. that a clickable icon is actually a "button" that toggles a filter) plus a manual screen-reader pass (not automated tooling alone, since automated tools miss narrative/logical-order issues).
Worked example
For the choropleth, a colorblind-safe blue-to-orange diverging scale plus a companion sortable table ("County, % change, rank") lets a screen-reader user get the same insight (which counties changed most) that a sighted user gets from the map's darkest regions.
Trade-offs and pitfalls
Building a full accessible-table alternative for every complex chart adds real engineering and design time; prioritize it for the charts that carry a decision-relevant insight, not for purely decorative or low-stakes visuals, and treat accessibility as a release-gating checklist item rather than a stretch goal.
