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Accessibility Score Points Weighting

Sean Needham avatar


With the Siteimprove Accessibility module, you can make your website(s) more accessible giving your visitors a better experience and improving your search engine optimization.

The Siteimprove Accessibility Score is a measure of how well your site performs against the automated Siteimprove accessibility checks.  Find out more in the article "What is the Accessibility Score?".

Our automated checks help you identify issues, make your progress visible, and prioritizes your work. The criteria that Siteimprove checks can be found on the Accessibility Score Breakdown. This article describes how the Accessibility scores are generated as well as which issues have the biggest impact on your Accessibility score.

Screenshot of the Accessibility overview page highlighting four sections: Score details, Overall score, Accessibility Score progress graph and the Score breakdown.

Point system explained

To generate a balanced score that reflects progression in Accessibility, we have designed an algorithm that ranks the issues we detect on your site. The Accessibility score breakdown page displays all the errors and warnings that are being checked.

The Web Content Accessibility Guidelines (WCAG) are part of Siteimprove’s automated Accessibility checks. We make a distinction between errors and warnings to distinguish between WCAG success criteria and best practices:

  • Errors: automatically determined failures to meet success criteria in WCAG.
  • Warnings: automatically determined failures to meet best practices in WCAG.

Besides these two categories, we are also using the A, AA, and AAA. (For more information please see article: Levels A, AA, AAA errors in Siteimprove Accessibility explained.)

With the categories and levels combined, we weigh the issues that occur on your website and reflect this using points, which in turn generates the Accessibility score.

How are the issues being weighed?

The majority of issues are being calculated site-wide, meaning that the whole site needs to be free of that particular issue in order to gain all of the points for it.

Here is a table showing how the points are distributed:

WCAG Level issue Category Weight 
A Errors 0.81
Warnings 0.25
AA Errors 0.53
Warnings 0.18
AAA Errors 0.33
Warnings 0.07

You can also gain up to 30 points for resolving all issues on a per page basis with different points available depending on what level the page sites within the site structure.

  • Pages at level 1 (i.e. your homepage) with multiple Level A/AA errors.
  • Pages at level 2 with multiple Level A/AA errors. 
  • Pages at level 3+ below with multiple Level A/AA errors. 

(To learn more about page levels, see article: How does Siteimprove define Page level?)

Page Level WCAG Level issue Weight 

Page Level 1

A/AA errors

3.0 / divided among the number of pages

Page Level 2

A/AA errors

6.0 / divided among the number of pages

Page Level 3+

A/AA errors

21.0 / divided among the number of pages

Your homepage (level 1) and pages directly off of it (level 2) will gain 9 Accessibility points and is a good place to start. As you tackle and resolve the issues affecting these pages you will also consequently be resolving some of the template issues that affect most or all of the site.

Note: PDFs with accessibility issues do not impact your sites Accessibility Score. This is due to the fact that not all sites or accounts have PDF checking enabled.

Example to help you choose which issue to tackle first.

If you need guidance on where to start, this example helps you make that decision for your website.

Besides the errors on at the different page levels mentioned previously, points are available for individual issues as well. Available points for an issue are divided equally across the pages that issue affects. Some organizations might have 50 pages and some 5000 pages to manage, but still gain the same amount of points upon completion.

Let’s take these two issues as an example:

A screenshot of a table taken from the Siteimprove platform showing the following information. Issue: Image link Is missing alternative text. Points you can gain: 0.28. Points already gained: 0.53. Issue: Redundant WAI-ARIA attribute. Points you can gain: 0.25. Points already gained: 0.00.

  1. Image link is missing alternative text (Level A, error category)
    • This is an A-level issue which will, at a maximum, add 0.81 points to your Accessibility score.
  2. Redundant WAI-ARIA attribute (Level A, warning category)
    • This is an A-level issue but in the warnings category, so it will give a maximum of 0.25 points to your Accessibility score.

You can see that for the first example, you can still gain 0.28 points while for the second example you can gain 0.25 points.

Let’s analyze what this means:

  • The "Image link is missing alternative text" issue has already increased your total Accessibility score by 0.53 so some of the work is already done. Combined with the remaining 0.28 this would end up with a total increase of 0.81 points as soon as this issue has been fixed site-wide.
  • Since no points are already gained, the "Redundant WAI-ARIA attribute" must be fixed site-wide to gain a total of 0.25 points.

Even if the points gained in the examples above are almost identical (0.28 and 0.25), the category (error or warning) is important to notice since one has a maximum of 0.81 and the other a max of 0.25. Besides checking the category, "Points already gained" shows that the site has already gained points for "Image link is missing alternative text", so it might be faster to eliminate this issue site-wide - as opposed to the "Redundant WAI-ARIA attribute" warning that has not gained any points yet and needs to be fixed site-wide.

Also, if addressing the remaining "Image link is missing alternative text" errors contributes to clearing errors from the Page Level checks, this can mean an added boost to your Accessibility score.

Siteimprove is here to help and guide you as much as possible. In the end, however, it’s up to your team to realize the changes. Depending on your expertise and time, some issues might be faster or easier to fix and therefore better to prioritize.

Because "Redundant WAI-ARIA attribute" is categorized as a warning and not an error, you don't get extra score benefit even if these pages are on levels 1, 2, or 3.

Summary

This can be a lot to take in. To gain the most accessibility points and therefore a higher Accessibility score, remember:

  1. Prioritize your A and AA errors based on your expertise and time.
  2. Check the total amount of points that can be gained per issue.
  3. Focus on resolving Pages and not just single Issues.

Following the summary points should enable you to gain a higher score faster and bring your site closer to being digitally accessible.

We hope this article gave you better insight in the score system of the Siteimprove Accessibility module. If you have any questions, please contact our support team.

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