Guide for setting accessibility targets 

This guide explains three methods for setting accessibility targets in Fable Engage. Each approach has its own strengths and considerations, and this article covers how to use each one.

  1. Compatibility Test task completion rate
  2. Accessible Usability Scale (AUS) and System Usability Scale (SUS)
  3. Create a custom AUS target
Black and white illustration of an arrow hitting the centre of a target

Option 1: Compatibility Test task completion rate

You can benchmark accessibility by setting a target for task completion rate in a Compatibility Test. A common target is 80%–100% task completion.

  • If less than 100% of testers complete the task, it indicates a barrier that prevented them from succeeding.
  • A completion rate of 80% is a good minimum benchmark, but 100% should be the ideal goal to ensure barrier-free accessibility.

Strengths

  • Only 1 Request needed per task flow
  • Requires fewer Requests (feedback from 5 testers per request)
  • CT results include blockers which are easily identifiable tester feedback
  • Blockers outline exactly why the completion rate is low, giving you tangible feedback

Considerations

  • Does not provide a detailed usability assessment
  • Focuses only on task completion, not user experience

Option 2: Accessible Usability Scale (AUS) and System Usability Scale (SUS)

You can benchmark accessibility by setting a target based on AUS and SUS scores.

What are AUS and SUS?

The System Usability Scale (SUS), developed in 1986 by John Brooke, is a well-established questionnaire used to assess overall usability. The Accessible Usability Scale (AUS) is a variation designed specifically for users of assistive technology.

The AUS was inspired by SUS and designed specifically to evaluate usability for assistive technology users.

Each scale includes 10 questions and results in a score out of 100. Learn more about AUS and SUS.

You can use either the average scores of AUS or SUS to set an accessibility target:

  • The average SUS score is 68, based on data from 500 studies.
  • The average AUS score is 65, derived from 2,100 usability sessions across different assistive technologies:
    • Screen magnification: 72 AUS average
    • Alternative navigation: 67 AUS average
    • Screen reader: 56 AUS average

Strengths

  • AUS offers a more detailed usability assessment
  • AUS scores come with qualitative insights from user feedback
  • The Requests that provide an AUS score (User interviews and Self-guided tasks) provide video recordings which add important context
  • If you are already familiar with SUS scores, then AUS scores will be easy to understand

Consideration

  • Requires more Requests (5-7 per key task flow) to generate reliable scores

Option 3: Create a custom AUS target

You can set a custom AUS target based on baseline testing.

How to conduct baseline testing

  1. Start by choosing the product or task flow you want to evaluate.
  2. Determine what the most important tasks are within the product or choose a single task flow to baseline. Some examples of common key task flows:
    • Create an account and log in
    • Search
    • Add to cart
    • Checkout
    • Contact support
  3. Decide which request types to use.
  4. To ensure a balanced distribution, run the requests with this combination of assistive technologies:
    • 3 screen reader users
    • 2 alternative navigation users
    • 2 screen magnification users
  5. Run 5-7 User Interviews or Self-Guided Tasks.
  6. Calculate the average AUS scores from the 5-7 requests.

Based on your AUS score results from your baseline testing, set a target that is realistically achievable. For example, if your baseline AUS score is 60, setting a target of 90 might be jump. Start with an achievable milestone and build from there.

Strengths

  • Personalized goal based on your starting level of accessibility
  • Allows for gradual improvement tracking
  • Ensure that your target is achievable by knowing what your baseline is
  • Establishing a baseline for your product encourages meaningful discussions about organizational commitments to accessibility

Consideration

  • Will require more time to do the initial baseline testing to determine a reasonable target

What to do after setting an accessibility target

Compatibility Test (Option 1)

After setting a target of 80% or 100% task completion you can conduct:

  • One Compatibility Test per key task flow
  • A Compatibility Test automatically consists of 5 testers per Request
  • To ensure a balanced distribution, select the Mixed users audience type

AUS score (Option 2 and 3)

After setting your target of either the average AUS score or a custom AUS score you can conduct:

  • 5-7 User Interviews or Self-Guided Tasks to get an AUS score for each key task.
  • You can average scores from at least 3 testers, but for a more robust result, test with 5–7 users using different assistive technologies.
  • To ensure a balanced distribution run the requests with this combination of assistive technologies:
    • 3 screen reader users
    • 2 alternative navigation users
    • 2 screen magnification users

Admins can track AUS averages over time through the Fable Engage company dashboard.

Once you begin running Requests, you can start measuring progress toward your goals.

Learn more about benchmarking accessibility.

Support and troubleshooting

If you have questions or require platform support, email support@makeitfable.com.