Accessibility Priority Tool
The Accessibility Priority Tool is a suggested mechanism for helping web content developers and organisations identify and correct issues that could reduce the ability of some people to access web content. The tool takes account of the needs and target audience of a site as well as a professional assessment of potential accessibility barriers when calculating an advice level for remediation. This advice level, in conjunction with the recorded information about the frequency and severity of each issue, can be used by the organisation to help prioritise efforts to improve the accessibility of their website.
The suggested Accessibility Priority Tool is not a solution to inaccessible web content, nor an alternative to the need for sites to comply with the Web Content Accessibility Guidelines advocated by the W3C. Rather, it is just a tool to help you decide which accessibility issues you should address now, and which you might be able to leave until a little later.
Accessibility Barrier Scores revisited
I have been a strong supporter of the W3C Web Content Accessibility Guidelines for more than a dozen years, and enthusiastically embraced the move to version two (WCAG 2.0) at the end of 2008. Although I continue to be a keen advocate for WCAG 2.0, I have in recent times become increasingly concerned by the tendency of some people to view web accessibility solely from the perspective of WCAG 2.0 compliance.
In November 2011, I discussed some of these concerns in the article “Accessibility Barrier Scores”. The article also outlined a suggested system for identifying potential web content accessibility barriers and their likely severity that could be used in conjunction with WCAG 2 when evaluating the accessibility of sites.
Over the last year, I have provided a number of clients with a completed version of the 2011 Access Barrier Score Excel file as an appendix to website accessibility review reports. In general they have found this appendix made it easier to see the extent and severity of problems and they also found the Remediation Priority generated by the system useful. I also received suggestions from clients, developers and accessibility practitioners about how the system might be improved.
Following this feedback, I have revised the scoring system and once again must thank Andrew Downie for his help with the Excel formulas. Thanks also to Russ Weakley, Janet Parker and Danny Thomas for their suggestions. As you see, I have also changed the name of the system to “Accessibility Priority Tool” (APT).
Introducing the Accessibility Priority Tool
I envisaged the Accessibility Barrier Scores system (2011) as being primarily an aid to help people evaluating the accessibility of web content communicate the relative importance of issues in a way that would be easy for clients to understand. The overall intention of the Accessibility Priority Tool is quite different.
This tool focuses on the needs of large organisations, such as government agencies, educational institutions or banking and finance companies, which may devolve responsibility for determining the accessibility of their content to a diverse group of people. The APT allows organisations to rank the perceived importance of accessibility barriers, in a worksheet that can be used by the different people who evaluate the accessibility of the web content, to identify and prioritise issues in a way that is consistent within the organisation.
The APT does not aim to measure how well a site might comply with WCAG 2.0. However the WCAG 2.0 Success Criteria related to the different accessibility barriers in the APT Excel worksheet have been included as a reference to aid users of the worksheet. These could be replaced with any other reference system (e.g. Section 508) that may be more relevant in a different environment.
Following feedback from Detlev Fischer (see comments) the attached Accessibility Priority Tool Excel file has been revised.
The differences between this tool and the 2011 Accessibility Barrier Score system, as well as a brief explanation of the reasons for these changes, are outlined below:
New Access Barrier Items
When preparing the original Accessibility Barrier Score, I really wanted to keep the number of access barriers as low as possible, but this meant that some issues got combined and others were overlooked. In hindsight I think I was a little too obsessive in this regard. The number of barrier items has increased from 26 to 33, and these are presented in the following categories: Text alternatives & colour, Structure & Navigation, Video & Audio, Forms, Data Tables, and Understandable.
I have also included two new categories:
- Use of Other Technologies – to accommodate the growing use of third-party components such as social networking tools or ticketing systems, which are often inaccessible. Sometimes these tools can cause a variety of accessibility issues and the aim of this section is to highlight which tools are the sources of the problems.
- Device Usability – to meet the need of an increasing number of clients who want to know if their site will work with smart phones and tablets. There is also an item to indicate the overall usability of the site with a screen reader. I know this may be contrary to the technology neutral (agnostic) approach of WCAG 2.0, but think website owners and developers will find it useful.
New Column for Importance Rank
The original Accessibility Barrier Score calculations (2011) were based only on two factors: How often are page components, which might cause problems, present on the site; and, the severity of those problems as determined by the person using the system to evaluate the site. When calculating the Remediation Priority, the Access Barrier Score system did not take into account how much importance the site owner (or external regulators) gave to a particular issue.
The Accessibility Priority Tool (2013) contains an additional column, “Importance Ranking”, which allows those with overall responsibility for the accessibility of a site to have an influence on how important they believe each barrier to be in relation to their particular circumstances. Each item is given a value of between 1- 5, with 1 being least important and 5 the most.
The intention of the Importance Ranking values is to reflect the overall objective of the site and the needs of the main target audience when determining the priority given to addressing the different identified access barriers. The importance rank should not be viewed as a proxy for WCAG 2.0 conformance levels. Different organisations will determine the importance ranking for each of the access barriers depending on their circumstances. The ranking values should be entered into the APT worksheet well before an accessibility evaluation of a site is undertaken, thereby enabling the organisation to have an input into the relative importance of the different access barriers that is independent of the objective severity of the barriers as determined by the accessibility evaluator.
The following examples are provided to help explain the aim of the Importance Ranking:
- A regulator (e.g. a government agency or large institution) may use it to set their overall priorities for the various issues.
- A client with a site aimed primarily at people who have hearing difficulties might decide to give a higher ranking to the need to provide a sign language alternative for video material when compared, for example, to a site devoted to opera.
- A site targeted at the elderly may give greater weighting to issues relating to text size and colour contrast, than might be the case with a site for young people.
- An educational or welfare site specifically for people with reading difficulties may decide to give the highest ranking to several issues that relate directly to their audience, even though in WCAG 2.0 terms these might be at Level AAA.
The Importance Ranking is just a tool for moderating the Access Barrier Advice (column F) calculated for each item. Since the importance rank values will be established by the organisation prior to the accessibility evaluation of a site or sites and not subject to change by those undertaking accessibility evaluations, I expect the Importance Ranking column in the excel worksheet will normally be hidden after it has been set and not displayed during site evaluations or in the in the final results.
The attached APT worksheet Excel file already contains Importance Ranking values for each item. These values are my opinions about how important each issue is, based on my experiences and personal prejudices. For example, I tend to give issues relating to needs of people with cognitive and reading difficulties a rank higher than that suggested by the conformance levels in WCAG 2.0.
If you wish to use the attached excel worksheet but believe some of the Importance Ranking values are not correct or do not reflect your needs please feel free to change them.
How to use the Accessibility Priority Tool
The Accessibility Priority Tool is an Excel worksheet which uses an inbuilt formula to calculate advice relating the potential accessibility issues (Access Barrier Advice) based on the information provided. The aim of the APT worksheet is to provide website owners and developers with a tool to help them prioritise their efforts in correcting issues that may prevent some people from accessing or using the content of the site.
The Excel sheet contains eight columns:
- Item (number)
- Description of Access Barrier
- Incidence score
- Severity score
- Access Barrier advice
- Importance Ranking – which may be displayed or hidden
Within the Description column there are 33 potential barriers to accessing web content, for example “Images without appropriate text alternatives (alt text)” and “Unable to programmatically identify form inputs (e.g. explicitly associated labels or title attribute)”. There are also items relating to the use of third-party page components such as embedded external ticketing systems, and how usable pages are with different devices including screen readers and smart phones.
Preparation: Determining the Importance Ranking (Excel column H – NB sometimes hidden)
Prior to using the Accessibility Priority Tool an importance rank value must be provided in the “Importance Ranking” column for each of the items (with a score of 1 for the least important through to 5 for the most important).
Who determines the importance of the items will depend who is responsible for the accessibility of the site and the circumstances of the accessibility evaluation. The following examples are provided to help explain this point.
- Government departments and large enterprise such as financial institutions, often have processes and teams for determining and monitoring the quality of websites. Those with overall responsibility for ensuring the accessibility of web content would enter the values into the Importance Ranking column (perhaps with the assistance of an accessibility specialist). In this situation, the importance rank values for various items are likely to be constant for the organisation. Many different people from within (and maybe outside) the organisation will be using APT worksheets with the same importance rankings to evaluate different pages (or page components).
- At the other end of the scale, there are small not-for-profit organisations without dedicated web teams. In these situations, the Importance Ranking values will need to be determined in advance by the accessibility evaluator consulting with representatives from the organisation and with reference to the objectives and target audience of the site.
- Some organisations may use the importance ranking as a way to prioritise work based on the native accessibility capabilities within the organisation. For example, basic issues that are easy to address within the organisation could be given a higher priority when compared to more complex issues that might require outside assistance.
The importance ranking (column H) would probably not be displayed in worksheets used by people evaluating the accessibility of the web content because the values would be constant for an organisation, and couldn’t be changed by the people undertaking evaluations. Also the visibility of the importance ranking could influence the impartiality of an accessibility evaluator.
As mentioned earlier, the APT Excel file contains suggested Importance Ranking values for each of the items. However, these values can be changed depending on how important each item is considered in different situations.
Evaluation: Incidence Score (Excel column D)
The Incidence score is a measure of how frequently the person using the tool believes that a particular barrier occurs on the site, or how frequently the way a site component is used does not meet the relevant accessibility requirements.
They enter an Incidence Score for each access barrier item using a five point scoring system:
0 – There is no incidence or occurrence of a failure to make the component accessible.
1 – The use of the page component or element causes access problems up to 25% of the time.
2 – The use of the page component or element causes access problems between 25% and 50% of the time.
3 – The use of the page component or element causes access problems between 50% and 75% of the time.
4 – The use of the page component or element causes access problems more than 75% of the time.
The following examples are provided to help explain the use of the Incidence Score:
- If there are 10 images in the content being reviewed, and 4 of those images have no alt text (item 1), the lack of a text alternative could cause an accessibility problem 40% of the time images are used, so the incidence score would be 2.
- If a site has just one CAPTCHA and it is inaccessible (item 5); then 100% of the times CAPTCHA is used could cause a problem, so the incidence score would be 4.
- If a site contains a number of pages with good content headings and sub-headings that use the correct mark-up, but on one page there are a few sub-headings that don’t use heading elements (item 9), then incidence score for the use of heading elements would be 1.
- If all the form inputs, which require the correct information to be entered, clearly identify when an error is made (item 28), then the incidence score would be 0
- However, if between 50% and 75% of the form inputs that identify errors, fail to provide a suggestion for correcting the error (item 29), then the incidence score would be 3
Evaluation: Severity Score (excel column E)
The person undertaking the accessibility evaluation uses the Severity score to rate the likely impact they believe each barrier or page component (column B) will have for someone with a disability.
The impact is rated with a Severity score of 1 to 5, where 1 is a minor inconvenience, and 5 indicates someone would be totally prevented from accessing the site content or functionality. For example:
1. Very minor inconvenience: Not likely to prevent anyone from accessing content, but could be a minor irritant.
2. Minor inconvenience: Not likely to prevent anyone from accessing content, but could affect the ability of some people to use a page.
3. Average inconvenience: Could make it difficult for some people to access content and use a page.
4. Major inconvenience: Could prevent some people from accessing or using page content.
5. Extreme inconvenience: Will prevent access to sections of the site or the ability to perform required functions.
Allocation of the severity rating will of course be subjective, and as such, is always liable to be influenced by the abilities, experiences, knowledge and foibles of the person making the decision. For example, if we take just three potential barriers that all relate to vision: text alternatives for images; colour contrast; and focus visible, the severity score given to each of these may vary greatly depending on your starting point. If you are solely concerned with the ability of screen reader users to use the web, the failure to include text alternatives is a major potential barrier, where as contrast ratio and focus visible are not barriers at all. On the other hand, if your concern relates primarily to diminished colour vision, contrast ratio and focus visible will be more important than text alternatives. And, for all web users, apart from those who are unable to perceive content visually, a failure to make focus visible is likely to be a significant barrier.
The subjective nature of determining the severity of an accessibility barrier is one of the reasons why I believe it is important for anyone using the suggested Accessibility Priority Tool (or any other process of accessibility evaluation) to have some knowledge of accessibility and assistive technologies.
Access Barrier Advice (excel column F)
When determining the final Access Barrier Advice, the Accessibility Priority Tool uses both the Incidence and Severity scores entered by the accessibility evaluator as well as the Importance Ranking values, which have been previously entered.
The Access Barrier Advice is presented as:
- Very High
NB: The Access Barrier Advice generated by the APT worksheet is just a suggestion and should not be solely relied upon. The advice may not accurately reflect the significance of a serious or important issue when the incidence is low. For example, a critical image with a missing text alternative among many (less important) images with good text alternatives will generate a maximum Access Barrier Advice of “High” when in fact it might be very important and critical to the accessibility of the site.
Comments (Excel column G)
This column should be used to provide comments about the relevant accessibility item and highlight examples of the barrier that are likely to have the greatest impact.
The comments column can be used to compensate for the relatively low Access Barrier Advice that can be given to important issues when there is a low incidence (as described above).
The Accessibility Priority Tool outlined in this article aims to provide web content developers and organisations with an Excel tool that will help them identify potential accessibility barriers to content on their sites and prioritise their efforts to address them.
The APT worksheet is a tool, and is not intended to be an alternative to, or replacement for, the Web Content Accessibility Guidelines or any of the WCAG2.0 checklists that are available. Also the tool will only be really effective when it used by people who are knowledgeable about web content accessibility and have experience evaluating the accessibility of sites.
I think this tool may be particularly useful to organisations that have a number of people monitoring the accessibility of sites, since the APT considers both the needs of the organisation and the audience for the site, as well as input from experienced accessibility evaluators, when determining advice relating to each of the potential accessibility barriers. Organisations can then combine this advice with knowledge of their own in-house accessibility capabilities when determining those issues they might be able to address quickly (low-hanging fruit) and those that might take longer and require greater resources.
I have tested the APT Excel worksheet with a variety of hypothetical situations and it seems to work fine apart from scenarios that involve a low incidence of a significant accessibility barrier (as mentioned in this document). For this reason, all the information (Incidence score, Severity score and Comments) provided for each of the access barrier items, and not just the Access Barrier Advice (Column F), should be used when determining remediation priorities.
Update 11 March 2013
As a result of the feedback from Detlev that identified the problem with using decimal points in the Excel formula, the Accessibility Priority Tool Excel file has been corrected, with considerable assistance from Andrew Downie, to remove the decimal point. In the attached APT Priority Tool Excel worksheet, Column ‘I’ is used to calculate the worksheet ‘Access Barrier Advice’ for each item that is presented in Column ‘F’. I have hidden Column ‘I’, but if you unhide it you can see the numerical calculation results.
I will be discussing this issue at the CSUN 2013 International Technology and Persons with Disabilities Conference in San Diego in the presentation, Accessibility is more than WCAG Compliance on Wednesday February 27 at 8.00 am.
Since the release of WCAG 2 there has been considerable debate about how to determine the accessibility of websites. Unfortunately, this is often presented as two simple choices: either using a checklist to determine the level of compliance/conformance with the specific Success Criteria; or, undertake some form of user testing by people who have different disabilities and/or who rely on different assistive technologies.
During this presentation I will look at the advantages and disadvantages of these two approaches. I will also report on the results of using the Access Barrier Scores during 2012 and the development of the Accessibility Priority Tool described in this article.