06 Sep Accessibility for Charts and Dashboards

In the digital age of data visualization, charts and dashboards have become essential tools for conveying complex information quickly and efficiently. They help users recognize patterns, extract insights, and make informed decisions. However, not all users perceive visual data the same way. For individuals with disabilities — such as visual impairments, cognitive limitations, or motor disabilities — traditional charts and dashboards can pose significant barriers. That’s where accessibility comes into play.

Accessibility for charts and dashboards focuses on ensuring that everyone, regardless of their abilities, can understand, interact with, and derive value from data visualizations. In this article, we delve into the best practices, tools, and principles that make data visualizations more inclusive, and why it’s more than just a checkmark for compliance.

Why Accessibility Matters

According to the World Health Organization, over a billion people — about 15% of the world’s population — live with some form of disability. That’s a substantial audience that deserves consideration when designing digital experiences. Accessible data visualizations are not only legally and ethically important but also offer improvements for everyone, including users in low-bandwidth environments or those on mobile devices.

Moreover, inclusive design can expand your reach. Public-facing dashboards used by government agencies, healthcare providers, and educational institutions need to work for all users — not just the majority. Accessibility ensures that no one is left behind when data is used to inform public policy, health awareness, or academic research.

Understanding the Barriers

Before diving into solutions, it’s crucial to recognize the main barriers users might face when engaging with charts and dashboards:

• Visual impairments: Color blindness, low vision, or complete blindness can limit or entirely prevent the interpretation of visual data.
• Mobility impairments: Users who rely on keyboard navigation or assistive devices may struggle with dashboards that require precise mouse control.
• Cognitive limitations: Some users might find complex charts overwhelming or hard to interpret without proper simplification or explanation.
• Language barriers: Poor labeling or unclear language in dashboards can make interpretation difficult for non-native speakers and people with language processing disorders.

Essential Principles for Accessibility

When aiming to create accessible charts and dashboards, the following principles offer a strong foundation:

1. Provide Text Alternatives

A chart is a visual representation of data — but for users who can’t see it, the visual elements must be supplemented by text alternatives. This could involve:

• Descriptive alt text summarizing the main trend or message of the chart.
• Accessible table versions of the underlying data to let users analyze the numbers directly.
• Dynamically generated, screen-reader-friendly annotations that explain the visual context.

For example, if presenting a line chart showing sales across four quarters, alt text might say: “Sales increased steadily each quarter, peaking at $20M in Q4.”

2. Use Color Thoughtfully

Color is a common method of encoding information — but relying solely on color can alienate users with color vision deficiencies. Consider the following best practices:

• Do not use color as the only distinguishing factor; use patterns, shapes, or labels in combination.
• Choose color palettes that are colorblind-safe. Tools like ColorBrewer can be helpful in achieving this.
• Ensure sufficient color contrast between chart elements and their backgrounds. This helps users with low vision as well as those in bright environments.

3. Keyboard Navigation and Focus Management

Interactive dashboards should be fully usable with keyboard inputs. This means users should be able to:

• Navigate between charts, filters, and controls using the Tab key.
• Understand the current focus area with a visible focus indicator.
• Use shortcuts or controls without requiring a mouse or touch input.

Focus management is critical for screen readers as well. When interactions change the display — such as updating filters — screen readers must be notified to avoid confusion.

4. Make Annotations and Legends Clear

Clarity is key in any data visualization, especially when catering to a diverse audience. Legends should be clear and concise, and chart elements should include informative tooltips or labels. Avoid ambiguous text like “Other” or “Miscellaneous” without providing further explanation.

Annotations, such as calling out peak values or events, can help users quickly understand a chart and make it easier for screen readers to convey essential insights.

Tools and Technologies that Support Accessibility

Modern charting libraries and business intelligence platforms are increasingly making strides in accessibility. Here are a few tools and features you should know about:

• D3.js: Offers flexibility for creating accessible charts, but requires manually adding ARIA labels and keyboard support.
• Highcharts: Has a built-in accessibility module that supports screen readers and keyboard navigation.
• Tableau: Provides accessibility features including screen reader support, text summaries, and keyboard navigation in Tableau Public dashboards.
• Microsoft Power BI: Includes capabilities like alt text, tab order settings, and accessibility checking features.

Incorporating Screen Readers

Screen readers translate on-screen content into speech or braille, making them vital for visually impaired users. However, charts are inherently visual, so they need proper ARIA (Accessible Rich Internet Applications) roles, labels, and descriptions to be screen-reader-friendly.

Recommendations include:

• Use ARIA roles such as role="img" or role="application" for interactive elements.
• Label all regions clearly with descriptive ARIA-labels.
• Provide a well-structured narrative summary for the chart, highlighting key data points and their implications.

Testing Accessibility

Testing is an integral part of making charts accessible. It’s important to include users with disabilities in your testing process. Automated tools can help, but they don’t catch everything. Some useful practices include:

• Manual screen reader testing using popular tools like NVDA, JAWS, or VoiceOver.
• Using browser extensions like Axe or the built-in accessibility inspector in Chrome and Firefox.
• Testing with keyboard-only navigation to ensure no functionality requires a mouse.

Make accessibility a part of your standard test suite — not something to be tacked on at the end.

Conclusion: Accessibility Is for Everyone

Creating accessible charts and dashboards is not just about meeting legal requirements or reaching a niche audience. It’s about building better, more usable, and inclusive products for everyone. Accessibility practices often lead to cleaner designs, clearer communication, and improved usability for all users — not just those with disabilities.

By adopting inclusive approaches early in the design process, using appropriate tools, and regularly testing with a diverse set of users, you can ensure that your data visualizations empower rather than exclude. Whether you’re a developer, designer, data analyst, or business stakeholder, remember: accessible data is usable data.