Best Practices for Designing Accessible Views

You created a great view, and you want to make sure that all of your users can see and understand the data that you've put together- but some users have visual or physical impairments. So what can you do?

Tableau supports several controls to enable you to build a view that complies with US Section 508 requirements when consuming a view in Tableau Online or Tableau Server that meets the Web Content Accessibility guidelines (WCAG 2.0 AA). Ensure that content shared from Tableau Online or Tableau Server follows the steps in Author Views for Accessibility and conforms to the following WCAG 2.0 AA principles:

  • Perceivable - Information and user interface components must be presented to users in a way that they can perceive. Consider including text alternatives and alternate ways to present the content.

  • Operable - The user interface components and navigation must be accessible to users from the different devices or methods that they use to interact with the view.
  • Understandable -The information presented in the view must be understandable to your users. For example, using clearly distinguishable names and labels for different elements shown in your view.

Follow the best practices described in this article and incorporate the steps described in Author Views for Accessibility, to build views that are accessible to all of your users when published on Tableau Server or Tableau Online.

Keep it simple

WCAG 2.0 AA principle: Understandable

You might have a lot of information that you want to communicate with your view. However, dense views can be difficult to understand or navigate using a screen reader or keyboard. Use the following guidelines to help you communicate everything that you want to without overwhelming your users with an over-packed view.

  • Aggregate your data whenever possible to help reduce the number of marks you are showing. Also, showing more than 1000 marks in the view can cause the view to be rendered by the server instead of the browser and server-rendered views are not yet supported for WCAG conformance.

    Users can also access the View Data page (enabled by default) to review the underlying data for the marks or can download the data from that page to an accessible application to view it that way.

    Example: This example shows two different bar chart views to illustrate the difference between a detailed and aggregated view.

    Not easily accessible - Too many marks More accessible - Aggregated view
    • This much detail makes the view harder to understand.

    • The view is showing over 5000 marks and does not include enough text to indicate what the different marks represent.

    • It is too difficult to use for users who need screen readers.

    • This example shows the same view with the data aggregated at a higher level.

    • Key data points are still included, but they are now easier for users to read and understand.

    • The number of marks is reduced from over 5000 to about 20.

    • Users can still read the underlying details for the marks by placing focus on the view and then pressing Enter to open the View Data page.

     

  • Consider using simple graphic elements like bar charts or line charts that allow you to use text, color, and shapes to add additional context to the view.

  • Limit the number of marks to only those that emphasize the most important data points.

For information and examples about how to build this type of view, see Keep it simple in Author Views for Accessibility.

 

Titles and captions

WCAG 2.0 AA principle: Perceivable, Understandable

Providing good descriptive text in titles and captions provides context to users who are using assistive technology, and can help them understand the data in your view. Use the following guidelines to adapt the visual nature of Tableau to meet the needs of all of your users.

  • Think about your views as a supplement to the text you use to describe it.

  • Use text in titles and captions to describe your visualizations and what you are showing.

  • Use simple, easy-to-understand language. Avoid jargon, acronyms, or abbreviations.

  • Don't include words like "image of" or "picture of" in your text descriptions, because screen readers sometimes already include this information.

  • Avoid using all capital letters (for example in headings or titles), because they can be difficult to read.

    Example: This example shows two different bar charts. One using very little text and the other using titles and captions to add context

    Not easily accessible - Too little text More accessible - Adding descriptive text to provide context
    • A one-word title is not descriptive enough.

    • The marks are differentiated by color and size. But without additional text, the context for these marks can be difficult to understand.

    • There is no caption or other explanatory text to help explain this view.

    • This example shows the same view, but includes additional explanatory text in both the title and the caption.

    • The same contrast color scale and size differentiators are used, but labels are added to the bar marks to give additional context.

For information and examples about how to build a view that includes text for context, see Show more text and make it helpful in Author Views for Accessibility.

 

Additional text

WCAG 2.0 AA principle: Perceivable, Understandable

Using text beyond just titles and captions throughout your view can help users understand the context of the different elements that you are showing, as well as help describe the relationship between the different controls (such as legends and filters) and your data.

Use the following guidelines when adding additional text:

  • Use text in headings on legends or filters to describe the control and what it does. You can also use text zones on a dashboard to add additional context for your visualizations to further describe what you are showing.

  • Refer to controls by label whenever possible. For example changing the label for a legend from Subcategory to Color key for product type can help users understand the relationship between the controls and the data.

  • If you include link text in your view, use text that describes where the link will take the user. For example, use link text like "Global Warming statistics for 1990-2000". Avoid wording like "Click here", "More", or "More information". These link text examples are too generic and can be confusing to users.

  • Consider using Natural Language Generation (NLG) tools to help produce data-driven, textual narratives for visualizations. For example Wordsmith from Automated Insights, Narratives for Tableau from Narrative Science, or the Natural Language Insights extension from ARRIA.

    Example: This example shows two bubble charts. One that uses only the text that shows by default when creating a view and one that adds context-specific text throughout the view to help convey meaning in the view.

    Not easily accessible - Too little text More accessible - More descriptive text
    • This view uses the default text only for the sheet title and the default labels for the filters and legend.

    • The marks are differentiated by size and color only.

    • There is no caption or other explanatory text included in the view to help provide context.

    • This example shows the same view, but includes additional explanatory text.

    • Additional text was added to the title and caption to explain the relationship of the marks and provide additional context about what the view is showing.

    • Mark labels are added to show profit numbers so that users don't have to rely on the color only to understand this information.

For information and examples about how to build a view that includes additional text for context, see Show more text and make it helpful in Author Views for Accessibility.

 

Color and contrast

WCAG 2.0 AA principle: Perceivable, Understandable

You can use color to help distinguish marks in your view. However, for users with visual impairments, using color alone doesn't always provide enough of a distinction, especially when there are many marks in a view. Use the following guidelines when using color in your views:

  • Tableau provides a color-blind palette that you can use to help you select appropriate colors for your view. For any color palette that you use, try to provide enough contrast and assign colors that differ from each other on the light-dark spectrum.

  • For line marks, use additional options like shapes, size and labels to help distinguish them.

  • Use contrast analyzer tools to help select the best text colors and backgrounds with sufficient contrast ratios. Make sure that color contrast for text is strong and meets the contrast ratio standards of 4.5:1 (3:1 for large text).

    Example: This example shows two line charts. One that uses color only to differentiate the lines and the other that uses more appropriate colors plus shapes to differentiate marks

    Not easily accessible - Using only color to differentiate marks More accessible - Using color and shape to differentiate marks
    • This view uses only color to distinguish the lines from one another.

    • The marks in the view are not using a color- palette that is fully accessible to users with visual impairments.

    • This example shows the same view, but uses both color and shape to identify the marks.

    • A color legend and a shape legend with clear titles identify what the colors and shapes represent in the view.

For information and examples about how to build a view that uses color to help distinguish marks, see Use color thoughtfully and provide contrast in Author Views for Accessibility.

 

Publishing your view

WCAG 2.0 AA principle: Perceivable, Operable, Understandable

To make your views available to your users, publish your view to Tableau Server or Tableau Online, in the toolbar menu, click Share/ Users can interact with the view and toolbar buttons using a screen reader or a keyboard. For more information, see Keyboard access for Tableau views.

Note: Tableau does not support WCAG conformance for web editing, so Web Edit permissions must be turned off in the published workbook.

For information about how to publish and embed workbooks, find the embed code to copy into your web pages, and turn off the toolbar, see Publish and share the view in Author Views for Accessibility.

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