Data Visualization
Data visualizations—such as charts, graphs, dashboards, maps, and other visual summaries—help people see patterns and relationships that may be hard to spot in raw numbers. At UC, data visualization shows up in reports, presentations, dashboards, research outputs, and communications to leadership and the broader community.
When visualizations are accessible, everyone can understand the insights, not just those who can see and interpret complex visuals easily. Accessible data visualization supports users with low vision, color vision differences, cognitive processing differences, and those who rely on assistive technologies to explore information.
Focus Areas for Accessible Data Visualization
Data visualization touches several Core Concepts at once. Focusing on these areas will address many of the most common barriers.
Alt Text: Provide meaningful descriptions of charts, graphs, maps, and other visuals. Alt text should summarize what the visualization shows and the key takeaway, not attempt to describe every pixel. For more complex visuals, pair concise alt text with a brief narrative description nearby that explains the main patterns, trends, or comparisons.
Color Contrast: Ensure that text, lines, and markers in charts and graphs have sufficient contrast against their background. Colors used to distinguish data series or categories should be clearly distinguishable, even for users with color vision differences. Avoid combinations that are hard to tell apart, and test your choices in grayscale or with a color contrast checker when possible.
Navigation & Order: Organize dashboards and multi‑panel visuals so information appears in a logical sequence. Important summaries and key metrics should be easy to locate, with more detailed views grouped nearby. When visualizations are interactive, make sure keyboard users can move through controls and data in a predictable order, and that information is announced in a sensible sequence by assistive technologies.
Copy Formatting: Use clear, concise labels, titles, and legends. Avoid overly long or technical labels where a shorter, plain‑language description would work. Axes, legends, and captions should explain what is being measured and how to interpret the visual, without requiring users to guess what lines, bars, or colors represent.
Hyperlinks: When visualizations include links, filters, or interactive controls, use labels that clearly describe what each control does. Users should be able to tell what will happen when they activate a button or filter without relying only on its position or color.
Technical: Choose tools and platforms that support accessible chart structures, keyboard navigation, and screen reader compatibility. Ensure that charts and dashboards expose meaningful labels, roles, and names behind the scenes so assistive technologies can interpret them. When this is not fully possible, provide alternate ways to access the same information, such as data tables and text summaries.
Sample Use Cases
Start with the main message rather than every detail. In nearby text or a caption, briefly state what the chart shows and what the viewer should take away, such as “Enrollment increased steadily from 2018 to 2024, with the largest growth in online programs.” Alt text can provide a concise summary, while the surrounding text offers more explanation. Make sure the underlying data is available in a table so users who cannot interpret the chart visually can still access the numbers.
Select colors that have strong contrast with the background and are distinguishable from each other. Avoid relying on red/green or other combinations that are hard to see for users with color vision differences. Use patterns, labels, or direct data labels to reinforce meaning, rather than depending on color alone. Test your color choices with a contrast checker and, if possible, preview them in grayscale or a color‑blindness simulator.
Organize the dashboard so related information is grouped together and the most important metrics appear in predictable locations, such as the top or upper‑left area. Use clear labels for filters, tabs, and controls, and avoid relying on hover‑only interactions that cannot be accessed via keyboard. Provide a short overview or “How to read this dashboard” note that explains what is on the screen and how to interact with it. Whenever feasible, include links to underlying data tables or summary views.
If the visualization tool has limited accessibility support, focus on providing equivalent information in alternate formats. Offer a data table that contains the key data points, and add text summaries that describe main trends, outliers, and comparisons. Make sure these alternatives are clearly linked or placed near the visualization so users know they are available. When choosing new tools or renewing licenses, consider accessibility support as part of the evaluation.
When you embed a chart in a report or slide deck, ensure that the chart title and labels are clear and descriptive. Add alt text that briefly explains what the chart is about and the main conclusion. In the surrounding text or speaker notes, describe the pattern or finding in words, such as “You can see that…” followed by the key observation. Include the underlying data in a table or an appendix when appropriate so readers have another way to access the information.