Severity

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Assessing impact severity

It’s important to consider how accessibility issues affect various people with disabilities. By assigning a severity level, we can prioritize issue remediation. The greater the issue affects a user’s ability to complete a task, then the greater the severity; thus, the more important it is to fix the issue.

Impact Severity Predicted Impact on Task Completion
NA There is no issue.
None (0) The issue is not likely to be noticed by the user and is not likely to affect task completion.
Minor (1) The issue is likely to be noticed by the user, but there are simple ways to overcome it or to avoid it; it is easy to remember it, to learn how to avoid or get around it. This issue is likely to marginally affect task completion.
Significant (2) The issue is likely to heavily affect progress towards task completion, for example by increasing the chances of making input or navigation errors or making things harder to understand. To overcome the barrier the user will likely have to back-up, follow a trial-and-error strategy, guess the proper action, or repeat an action several times.
Critical (3) The issue is so significant that it is likely to stop users from completing the task. There are no alternative ways (known to the users) that can be followed to complete the task.

Severity scale adapted from the Barrier Walkthrough method, developed by Giorgio Brajnik.

User Profiles

For the sake of testing, we can generalize common groups of people with disabilities into user profiles. Each user profile includes the WCAG 2.0 and some 2.1 success criteria that directly affects that group. You may wish to refer back to these profiles after you have fully tested a page.

People who are blind who use screen reader software and alternative input methods (keyboard, braille display, swipe gestures) to work with technology.

Relevant WCAG Success Criteria

People with limited vision who use screen magnification software or display modifications to work with technology.

Relevant WCAG Success Criteria

People with limited color perception who cannot use technology features that rely on color perception.

Relevant WCAG Success Criteria

People who are deaf or hard of hearing who cannot use technology features that rely on sound.

Relevant WCAG Success Criteria

People who have speech impairments who cannot use technology features that rely on speech.

Relevant WCAG Success Criteria

People with mobility impairments that limit dexterity, reach, or strength who use alternative input methods (keyboard, switch device, speech) to work with technology.

Relevant WCAG Success Criteria

People with cognitive impairments that limit language, cognitive, or learning abilities who cannot use technology features that are complex, and who may use assistive technologies (speech input, screen reader software) to work with technology.

Relevant WCAG Success Criteria

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