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Copyright © 2013 W3C® (MIT, ERCIM, Keio, Beihang), All Rights Reserved. W3C liability, trademark and document use rules apply.
This document provides guidance on evaluating the extent of conformance of websites to the Web Content Accessibility Guidelines (WCAG) 2.0. It describes a procedure, highlights considerations, and promotes good practice to guide accessibility evaluators in creating conformance evaluation reports. It does not provide instructions on a feature-by-feature evaluation of web content; it relies on WCAG 2.0 techniques for this. It is an informative resource that is part of a series of W3C/WAI resources on Evaluating Websites for Accessibility and that complements the existing WCAG 2.0 Documents. It does not define additional WCAG 2.0 requirements nor does it replace or supersede it in any way.
The methodology described in this document is intended for use by people who are experienced in accessibility evaluation using WCAG 2.0 and its supporting resources. It is primarily designed for evaluating existing websites, for example to learn about and monitor their level of accessibility, but it can also be useful during earlier development stages of website creation. It is applicable to static and dynamically generated websites, mobile websites and applications, and any other type of websites. It is independent of particular web technologies, evaluation tools, web browsers, assistive technologies, and other software, and it is suitable for use in different evaluation contexts, including self-assessment and third-party evaluation.
[For Review: Significantly rewritten (see previous Abstract) to reflect group discussions and to address comment 1, comment 2, and comment 20.]
This section describes the status of this document at the time of its publication. Other documents may supersede this document. A list of current W3C publications and the latest revision of this technical report can be found in the W3C technical reports index at http://www.w3.org/TR/.
This 19 November 2013 Editors Draft of Website Accessibility Conformance Evaluation Methodology (WCAG-EM) 1.0 addresses the comments received on the previously published Working Draft of 26 February 2013. It addresses all issues raised though some sections may need further refinement.
This document is intended to be published and maintained as an informative W3C Working Group Note after review and refinement. The WCAG 2.0 Evaluation Methodology Task Force (Eval TF) invites discussion and feedback on this document by developers, evaluators, researchers, and others with interest in web accessibility evaluation.
Please send comments on this Editors Draft of Website Accessibility Conformance Evaluation Methodology 1.0 to public-wai-evaltf@w3.org (publicly visible mailing list archive). These comments will be considered in the internal discussions of Eval TF.
Publication as Editors Draft does not imply endorsement by the W3C Membership. This is a draft document and may be updated, replaced or obsoleted by other documents at any time. It is inappropriate to cite this document as other than work in progress.
This document has been produced by the WCAG 2.0 Evaluation Methodology Task Force (Eval TF, a joint task force of the Web Content Accessibility Guidelines Working Group (WCAG WG) and Evaluation and Repair Tools Working Group (ERT WG), as part of the Web Accessibility Initiative (WAI) Technical Activity.
This document was produced by two groups operating under the 5 February 2004 W3C Patent Policy. The groups do not expect this document to become a W3C Recommendation. W3C maintains a public list of any patent disclosures for WCAG WG and public list of any patent disclosures for ERT WG made in connection with the deliverables of each group; these pages also include instructions for disclosing a patent. An individual who has actual knowledge of a patent which the individual believes contains Essential Claim(s) must disclose the information in accordance with section 6 of the W3C Patent Policy.
Evaluating the extent to which a website conforms to the Web Content Accessibility Guidelines (WCAG) 2.0 is a process involving several steps. The activities carried out within these steps are influenced by many aspects such as the type of website (e.g. static, dynamic, mobile, etc.), its size, complexity, and the technologies used to create it (e.g. HTML, PDF, etc.), how much knowledge the evaluators have of how the website was or is being developed (e.g. white-box, black-box, or gray-box testing), as well as the main purpose for the evaluation (e.g. to issue an accessibility statement, to plan a redesign process, to do research, etc.).
This methodology, the Website Accessibility Conformance Evaluation Methodology (WCAG-EM) 1.0, describes the steps that are common to website conformance evaluation processes and highlights considerations to help evaluators apply these steps in the context of a particular website. Following this methodology helps evaluators to apply good practice, avoid common mistakes, and achieve more comparable results. It supports common approaches and understanding for evaluating the extent of conformance of websites to WCAG 2.0, though in the majority of use cases it does not directly result into WCAG 2.0 conformance claims.
Also, this methodology does not in any way add to or change the requirements defined by the normative WCAG 2.0 standard, nor does it provide instructions on feature-by-feature evaluation of web content. The methodology relies on WCAG 2.0 techniques such as the Techniques for WCAG 2.0 documented by W3C/WAI, but is not limited to this set of techniques.
[For Review: Significantly rewritten (see previous Introduction) to reflect group discussions and to address comment 20.]
In many situations it is necessary to evaluate the accessibility of a website, for example before releasing, acquiring, or redesigning the website. Periodic evaluation is also useful for monitoring the accessibility performance of websites over time. WCAG-EM is for anyone who wants to follow a common procedure for conformance evaluation of websites to WCAG 2.0. This includes:
[For Review: Significantly rewritten (see previous "Purpose of this document") and merged with previous "Scope of this document" to reflect group discussions and to address comment 20.]
WCAG 2.0 defines conformance requirements for individual web pages rather than for entire websites. It also defines the optional conformance claims that can be made to cover individual web pages, series of web pages such as a multi-page form, and multiple related web pages such as a website. However, conformance claims in WCAG 2.0 can only be made to cover specific web pages that are known to satisfy each conformance requirement. This includes when all web pages that are in the scope of a conformance claim have been each evaluated or created in a process that ensures that they each satisfy all the conformance requirements.
WCAG 2.0 conformance claims cannot be made for entire websites based upon the evaluation of a selected sub-set of web pages and functionality alone, as it is always possible that there will be unidentified conformance errors on these websites. However, in the majority of use cases of this methodology only a sample of web pages and functionality from a website is selected for evaluation. Thus in the majority of use cases, using WCAG-EM does not directly result into WCAG 2.0 conformance claims for the target websites. Instead, Step 5.b provides guidance on how to make "Accessibility Conformance Evaluation Statements" for websites that have been evaluated according to WCAG-EM.
[For Review: New section that addresses discussion during telco of 25 July, telco of 12 September, telco of 17 October, and comment 81.]
The information below related to accessibility, WCAG 2.0, and evaluation is important background for using this methodology:
The following documents introduce the essential components of web accessibility and how people with disabilities use the Web, and are critical for understanding the broader context of web accessibility evaluation:
A multi-page resource suite that outlines different approaches for evaluating websites for accessibility. The following resources are particularly important in this context:
Internationally recognized standard explaining how to make web content more accessible to people with disabilities. The following resources are particularly important in this context:
For the purposes of this document, the following terms and definitions apply:
When a web page is one of a series of web pages presenting a process (i.e., a sequence of steps that need to be completed in order to accomplish an activity), all web pages in the process conform at the specified level or better. (Conformance is not possible at a particular level if any page in the process does not conform at that level or better.)
Satisfying all the requirements of a given standard, guideline or specification
The content would not conform if that technology is turned off or is not supported
Content patterns that are filled in by authors or the authoring tool to produce web content for end users (e.g., document templates, content management templates, presentation themes). Often templates will pre-specify at least some authoring decisions.
A non-embedded resource obtained from a single URI using HTTP plus any other resources that are used in the rendering or intended to be rendered together with it by a user agent
WCAG-EM is used for thorough evaluation of the extent of conformance of websites to WCAG 2.0. Before applying WCAG-EM on an entire website it is usually good to do a preliminary evaluation of different web pages from the target website to identify obvious conformance errors and to develop an overall understanding of the accessibility performance of the website. Easy Checks - A First Review of Web Accessibility describes an approach for such preliminary evaluation that is complementary to this methodology.
Users of WCAG-EM are assumed to be knowledgeable of WCAG 2.0, accessible web design, assistive technologies, and of how people with different disabilities use the Web. This includes understanding of the relevant web technologies, barriers that people with disabilities experience, assistive technologies and approaches that people with disabilities use, and evaluation techniques and tools to identify potential barriers for people with disabilities. In particular, it is assumed that users of WCAG-EM are deeply familiar with the resources listed in section Background Reading.
WCAG-EM is independent of any particular web accessibility evaluation tool, web browser, and other software tool. However, web accessibility evaluation tools significantly assist evaluators during the evaluation process and contribute to more effective evaluation. For example, some web accessibility evaluation tools can scan entire websites to help identify relevant pages for manual evaluation. Tools can also assist in manually evaluating the many checks that are not automatable. Selecting Web Accessibility Evaluation Tools provides further guidance beyond the scope of this document.
WCAG-EM can be carried out by an individual evaluator with the skills described in section Required Expertise. However, using the combined expertise of review teams provides better coverage for the required skills and helps identify accessibility barriers more effectively. While not required for using this methodology, it is recommended to employ review teams for conformance evaluation of websites. Using Combined Expertise to Evaluate Web Accessibility provides further guidance beyond the scope of this document.
Involving people with disabilities and people with aging-related impairments helps identify additional accessibility barriers that are not easily discovered by the evaluators alone. While not required for using this methodology, it is strongly recommended to involve real people with a wide range of abilities during the evaluation process. Involving Users in Web Accessibility Evaluation provides further guidance beyond the scope of this document.
WCAG-EM is designed for evaluating full, self-enclosed websites. This includes websites of organizations, entities, persons, events, products, and services. It also includes mobile websites and applications. Specific examples include:
A website can be part of a larger website, such as the online shop in the examples above. It can also be a clearly separable version of the website such as the mobile or Dutch language versions of the website in the examples above. WCAG-EM can be applied to any such determinable website, regardless if it is part of a larger website or the larger website itself. The exact definition of a target website to be evaluated is determined as part of Step 1.a.
When a target website is defined for evaluation, it is essential that all web pages and functionality that are within the scope of this website definition are considered for evaluation. Excluding such aspects of a website from the scope of evaluation would conflict with the WCAG 2.0 conformance requirements for full pages and complete processes, or otherwise distort the evaluation results.
In the diagram above, the university website is made of the distinct areas "Information for Students", "Information for Lecturers", "Courseware Application", and "Library Application". The "Courseware Application" includes "Physics Courses", "Medical Courses", and "History Courses" that are aggregated into the application. Also, the university website has individual web pages such as legal notices, sitemap, and others that are common to all areas.
In the example above, if the university website in its entirety is defined as the target for evaluation then all of the depicted areas are within the scope of the evaluation. This includes any aggregated and embedded content such as maps of the campus, forms for online payments, and discussion boards, including when such parts originate from third-party sources.
Similarly, if only a website area such as the "Courseware Application" is defined as the target for evaluation then all the parts of this area are within the scope of the evaluation. In this case it would include all depicted courses, as well as the individual web pages that are common to all areas of the university (see also: definition for Common Web Pages).
WCAG-EM is applicable to any website including dynamically generated websites, rich web applications, mobile websites and other types of websites. Some particular types of websites include:
WCAG-EM is flexible to allow its applicability in different situations and contexts. This section provides guidance for applying this methodology in some of these situations.
Conformance evaluation according to this methodology may be re-run after a short period, for example when issues are identified and repaired by the website owner or website developer, or periodically to monitor progress. In such cases, for the issues that were identified, include at least:
This section defines the stages and activities of an evaluation procedure. The stages are not necessarily sequential. Also the exact sequence of the activities carried out during the evaluation stages depends on the type of website, the purpose of the evaluation, and the process used by the evaluator. Some of the activities overlap or may be carried out in parallel. The following diagram illustrates the iterations between the stages defined in this section:
The workflow diagram depicts each of the five steps defined in this section with an arrow to the next step and arrows back to all of the previous steps. This way evaluators can proceed from one step to the next and return to any preceding step in the process whenever the evaluation reveals a need to return to any one of the previous steps: 1. Define the Evaluation Scope; 2. Explore the Target Website; 3. Select a Representative Sample; 4. Audit the Selected Sample and 5. Report the Evaluation Findings.
Note: See also considerations for Particular Evaluation Contexts that may influence how an evaluation procedure is carried out.
Methodology Requirement 1: Define the evaluation scope according to Methodology Requirement 1.a, Methodology Requirement 1.b and optionally Methodology Requirement 1.c and Methodology Requirement 1.d.
During this step the overall scope of the evaluation is defined. It is a fundamental step that affects the subsequent steps in the evaluation procedure and is ideally carried out together with the evaluation commissioner (who may or may not be the website owner) to ensure common expectations about the scope of the evaluation. Some exploration throughout this stage may be necessary to understand the full scope of the website and the required evaluation (see Explore the Target Website).
Methodology Requirement 1.a: Define the target website according to Scope of Applicability, so that for each web page it is unambiguous whether it is within the scope of evaluation or not.
During this step the target website (the web pages and states of web pages that are in scope of the evaluation) is documented. This scope of the website is defined according to the terms established in section Scope of Applicability.
To avoid later mismatches of expectations between the evaluator, evaluation commissioner, and readers of the resulting evaluation report, it is important to define the target website in such a way that for each web page it is unambiguous whether it is within scope or not. Formalizations such as regular expressions and listings of web addresses (URIs) are recommended where possible.
It is also important to document any particular aspects of the target website to support its identification. This includes:
[For Review: This addresses comment 35 (no change).]
Methodology Requirement 1.b: Select a target WCAG 2.0 conformance level ("A", "AA", or "AAA") for the evaluation.
Part of initiating the evaluation process is to define the target WCAG 2.0 conformance level ("A", "AA", or "AAA") to evaluate for. WCAG 2.0 Level AA is the generally accepted and recommended target.
Note: It is often useful to evaluate beyond the conformance target of the website to get a more complete picture of its accessibility performance. For example, while a website might not fully meet a particular conformance level, it might meet individual requirements from a higher conformance level. Having this information can help plan future improvements more effectively.
[For Review: Updated links to new Understanding Techniques for WCAG Success Criteria page — do we still need all the content in this section?.]
Methodology Requirement 1.c: Define any initial sets of techniques and failures that will be used to evaluate conformance to WCAG 2.0 Success Criteria. (Optional).
Techniques and failures in the context of WCAG 2.0 are informative and not required for determining conformance with WCAG 2.0; WCAG 2.0 Success Criteria are written as testable statements. Techniques provide documented ways of satisfying WCAG 2.0 Success Criteria and failures document commonly made mistakes. More information on techniques and failures is provided in WCAG 2.0 Layers of Guidance.
W3C/WAI provides a set of publicly documented Techniques for WCAG 2.0. However, it is not necessary to use these particular techniques. In fact, in some situations, such as in a closed network, it may be necessary to use techniques that are specifically developed to the particular needs of the users of that network. Individuals and organizations developing techniques have to employ methods for establishing the technique's ability to satisfy the WCAG 2.0 Success Criteria.
While optional, it is good practice to specify initial sets (or sources) of techniques and failures to be used during the evaluation, as it helps to ensure consistent expectation between the evaluator and the evaluation commissioner. This definition is typically refined in later stages of the evaluation process, for example during the website exploration and evaluation stages. Step 4.c: Use WCAG 2.0 Techniques and Failures Where Possible (Optional) provides more guidance on using techniques and failures during evaluation.
Methodology Requirement 1.d: Define any additional evaluation requirements agreed on between the evaluator and evaluation commissioner (optional).
[For Review: Proposed change this section as discussed on mailing list and in telco 18 July, and telco 5 september, to be more flexible and open for additional requirements/whishes from the evaluation commissioner(s). This section now presumes that the minimum requirements for reporting are set in Step 5: Report the Evaluation Findings with examples in Appendix C. Because the requirements are additional to the minimum requirements, the step is optional. Please review. Also look at the diff version provided in the agenda of telco for 5 september for small changes in the document as a result of changing the title and presuming that step 5 will contain the minimum requirements. This also covers comment 36 and comment 37.]
An evaluation commissioner may be interested in additional information beyond what is needed to evalaute the extent of conformance of the target website to WCAG 2.0. For example, an evaluation commissioner might be interested in:
Such additional evaluation requirements that are agreed on with the evaluator need to be clarified early on and documented. This also needed to be reflected in the resulting report, for example to clarify how the selection of web pages was carried out.
Methodology Requirement 2: Explore the website to be evaluated according to Methodology Requirement 2.a, Methodology Requirement 2.b, Methodology Requirement 2.c, and Methodology Requirement 2.d.
During this step the evaluator explores the target website to be evaluated, to develop an initial understanding of the website and its use, purpose, and functionality. Much of this will not be immediately apparent to evaluators, in particular to those from outside the development team. In some cases it is also not possible to exhaustively identify and list all functionality, types of web pages, and technologies used to realize the website and its applications. The initial exploration carried out in this step is typically refined in the later stages Step 3: Select a Representative Sample and Step 4: Audit the Selected Sample, as the evaluator learns more about the target website. Involvement of website owners and website developers can help evaluators make their explorations more effective.
Note: Carrying out initial cursory checks during this stage helps identify web pages that are relevant for more detailed evaluation later on. For example, an evaluator may identify web pages that seem to be lacking color contrast, document structure, or consistent navigation, and note them down for more detailed evaluation later on.
Note: To carry out this step it is critical that the evaluator has access to all the relevant parts of the website. For example, it may be necessary to create accounts or otherwise provide access to restricted areas of a website that are part of the evaluation.
Methodology Requirement 2.a: Identify and document the common web pages of the target website.
Explore the target website to identfy and document its common web pages. Typically these are linked directly from the main entry point (home page) of the target website, and often linked from the header, navigation, and footer sections of other web pages. The outcome of this step is a list of all common web pages.
Methodology Requirement 2.b: Identify and document an initial list of core functionality of the target website.
Explore the target website to identify and document its core functionality. While some functionality will be easy to identify, others will need more deliberate discovery. For example, an online shop is expected to have a payment function though it might be less easy to identify that it also has a currency conversion function that is core to the particular context of the online shop. The outcome of this step is a list of functionality that users can perform on the website, for example:
Note: The purpose of this step is not to exhaustively identify all functionality of a website but to determine those that are core to the purpose and goal of the target website. This will inform later selection of web pages and their evaluation. Other functionality will also be included in the evaluation but through other selection mechanisms.
Methodology Requirement 2.c: Identify and document the types of web pages.
Web pages with varying styles, layouts, structures, and functionality often have different implementations of accessibility features. They are also often generated by different templates and authored by different people. Web pages may also appear differently, behave differently, and contain different content depending on the particular user. The outcome of this step is a list of the different types of web pages (as opposed to instances of web pages), including states of web pages, that appear on the target website.
Examples of web page types include:
Methodology Requirement 2.d: Identify and document the technologies relied upon to provide the website.
During this step the web technologies relied upon to provide the website are identified and documented. This includes base web technologies such as HTML and CSS, auxiliary web technologies such as Java, JavaScript and WAI-ARIA, as well as specific web technologies such as SMIL and SVG. The outcome of this step is a list of technologies that are relied upon according to WCAG 2.0.
Only the web technologies that are relied upon to provide the website need to be identified for evaluation. This relates closely to the WCAG 2.0 concepts of conforming alternate versions and non-interference.
Note: Where possible, it is often also useful to identify the libraries and components used to create the website, such as Dojo, JQuery, and others. Particularly for web applications, much of the accessibility support is built into these libraries and components, and evaluation can become more effective and efficient when these are identified.
Methodology Requirement 3.c: Identify and document other web pages that are relevant to people with disabilities and to accessibility of the website.
Some websites include web pages that are relevant for people with disabilities and accessibility of the website. The outcome of this step is a documentation of such web pages. This includes:
Methodology Requirement 3: Select a representative sample of web pages from the website according to Methodology Requirement 3.a, Methodology Requirement 3.b, Methodology Requirement 3.c, Methodology Requirement 3.d, Methodology Requirement 3.e and optionally Methodology Requirement 3.f.
While ideally every web page of a website is evaluated, usually this is not possible on most websites. In cases where all web pages can be evaluated, this sampling procedure can be skipped and the selected sample is considered to be the entire website in the remaining steps.
[For Review: Proposal for explanation of the factors has been added. Please review.]
Exploration of the target website in Step 2: Explore the Target Website (within the scope set in Step 1: Define the Evaluation Scope) provides sufficient understanding of the website to facilitate selection of a sample of web pages that is within the scope and representative of the entire target website with reasonable confidence. The size of the sample needed for an accessibility evaluation evaluation with reasonable confidence depends on different factors. Below are a few examples of these factors and how they may aditionally influence the size of the sample:
The web pages identified through the exploration will typically relate to more than one design aspect. For example, web pages with particular functionality such as scripting, multimedia, and forms will typically also use technologies such as Flash, JavaScript, PDF, Silverlight, and WAI-ARIA, and in many cases these web pages may have different design to others. Careful selection of web pages can significantly reduce the required sample size while maintaining appropriate representation of the entire website.
Methodology Requirement 3.a: Include all common web pages into the selected sample of web pages.
All common web pages, including the common states of these web pages for web applications, are part of the selected sample. These web pages are identified in step Step 2.a: Identify Common Web Pages of the Website.
Methodology Requirement 3.b: Include (where applicable and available) of each (1) common functionality, (2) distinct types of web pages, and (3) web technologies into the selected sample of web pages.
From the variety and types of web pages identified in Step 2: Explore the Target Website (within the scope of the evaluation as defined per Step 1: Define the Evaluation Scope), select at least one distinct web page for all of the following features (where applicable and available):
Note: Every one of the features may require more pages depending on the distinct pages that have been identified. A selected web page could however also have any number of these features. For example, a selected web page could be used to represent the use of forms and scripting at the same time. The important aspect is to select at least one distinct web page for each relevant feature identified on the website, though more web pages may be necessary depending on the complexity of the website.
Methodology Requirement 3.c: Include other web pages relevant for people with disabilities and accessibility into the selected sample of web pages.
Websites frequently include web pages that are relevant for people with disabilities and accessibility but do not explicitly match the criteria described in the previous sections. These web pages are also part of the selected sample. They typically include:
Methodology Requirement 3.d: Include all web pages that are part of a complete process.
The selected sample has to include all web pages that belong to a series of web pages presenting a complete process. No web page in the selected sample may be part of a process without all other web pages that are part of that process to be also included into the selected sample.
Methodology Requirement 3.e: Include a randomly selected sample.
A randomly selected portion of the sample, even if it is small, can act as a simple verification indicator of the results found with the structured sample. In that case, a few web pages would then be sufficient to increase confidence in the results of the evaluation. Therefore, from the scope of the website as defined in Step 1: Define the Evaluation Scope, randomly select at least 10 to 15 percent of the number of web pages in the sample with a minimum of 5 randomly selected web pages (if available on the website). How the random sample was selected is reported in Step 5.a: Provide Documentation for Each Step.
[Editor Note: We plan to add more information about random sampling in an appendix or in a seperate document. Possibly with some examples. See discussion on the list and minutes of telco of 12 september.]
Methodology Requirement 3.f: Filter the sample to eliminate excessive redundancies.
[For Discussion: Discussed in the telco of 19 september. Peter proposed "to put "uniqueness" of items in the sample into step 3.e. Then 3.f can be a discussion about "appearing to be similar", and about hetero-/homogeneity".]
Once a sample has been selected according to Methodology Requirement 3.a, Methodology Requirement 3.b, Methodology Requirement 3.c, Methodology Requirement 3.d, and Methodology Requirement 3.e, evaluators may identify web pages that are completely identical with other web pages in the sample. Replace these redundant web pages in the sample with other web pages using the same Methodology Requirement as for the removed web pages.
Note: Redundancy can also indicate that a website is homogenous.
Methodology Requirement 4: Audit the selected sample of web pages according to Methodology Requirement 4.a, Methodology Requirement 4.b, and optionally, Methodology Requirement 4.c, Methodology Requirement 4.d and Methodology Requirement 4.e.
WCAG 2.0 defines five conformance requirements that need to be met for each web page in the sample selected per Step 3: Select a Representative Sample. This includes checking whether each WCAG 2.0 Success Criterion in the target conformance level (per Step 1.b: Define the Conformance Target) has been met or not met for each of these web pages.
Note: Many web pages will have repetitive content, such as the header, navigation, and other common components that may not need to be re-evaluated on each occurrence. Depending on the additional requirements for evaluation (optional) as defined by Step 1.d: Define Additional Requirements for Evaluation (Optional), an evaluator may not need to continue to identify successes and failures in meeting the conformance target for these repetitive elements on every web page. Step 5: Report the Evaluation Findings provides more guidance on reporting.
Note: According to WCAG 2.0, if there is no content related to a success criteria (for example, no video), then the success criteria is "satisfied". In such cases, an evaluator may use text such as "not applicable" as a description associated to the outcome "satisfied", to denote the particular situation where a success criterion was satisfied because no relevant content was applicable.
Proposal: "According to WCAG 2.0, Success Criteria to which there is no matching content are satisfied. ."
[For Review: This addresses comment 58, comment 59, comment 60, comment 61, comment 62, comment 63 and comment 57 (no change).]
Methodology Requirement 4.a: Check that each web page in the selected sample per Step 3: Select a Representative Sample meets each of the WCAG 2.0 conformance requirements, including all WCAG 2.0 Success Criteria relevant to the target conformance level (as per Step 1.b: Define the Conformance Target).
[For Review: Changed the title from "step 4.a: Check for the Broadest Variety of Use Cases" to "step 4.a: Check web pages fort WCAG2.0 conformance requirements". This addresses comment 65. Added the text "Note that techniques and failures in the context of WCAG 2.0 are only informative" to the text below addressing comment 74.]
For each web page in the sample selected per Step 3: Select a Representative Sample, check whether each of the WCAG 2.0 conformance requirements have been met, including all WCAG 2.0 Success Criteria relevant to the target conformance level (as per Step 1.b: Define the Conformance Target). Note that techniques and failures in the context of WCAG 2.0 are only informative.
[For Review: Take the text below out ("To carry out ... for more guidance."). It is not relevant to this section and it is addressed elsewhere in the document. This is about checking for conformance requirements. Use cases influence the selection of the sample and are addressed earlier. Addresses comment 66, comment 67, comment 68 and comment 64 (no change). ]
To carry out an evaluation effectively, it is often useful to construct and apply personas, use cases, and scenarios of users with a variety of abilities and using different web browsing techniques, including assistive technology and adaptive strategies. It is critical to consider the broadest possible spectrum of use cases to help identify issues that may occur to different audiences. It is strongly recommended to also involve real users during this process, to help identify issues that may not be easily identified through expert testing alone. See Involving Users in Evaluating Web Accessibility for more guidance.
[For Discussion: Can we add more guidance below? See comment 66: Can we get guidance out of WCAG as proposed in comment 66?]
This assessment also needs to be complemented with focused testing of particular situations including:
Note: Templates are often used to create many web pages, sometimes entire parts of a website. While evaluating templates is optional in this methodology, in some contexts it can be helpful to check templates on their own. Evaluating templates may identify potential issues that may not be easily identified through evaluating individual instances of web pages. However, issues identified in templates alone do not necessarily imply that these issues occur on the website and need to be validated on individual instances of web pages. Also, identifying no issues in templates does not necessarily imply that no issues occur on instances of web pages.
Methodology Requirement 4.b: Check if accessibility features provided on the website are accessibility supported.
[For Review: This addresses comment 69, comment 70 and comment 71.]
To ensure that the accessibility features such as text-alternatives, captions, keyboard access are actually usable in practice, each of these accessibility features has to be accessibility supported. The Level of Assistive Technology Support Needed for "Accessibility Support" defined by WCAG 2.0 needs to be supported throughout the website.
In some situations techniques for meeting WCAG 2.0 and repositories on accessibility support provide insights on the level of support for accessibility features in particular combinations of web technologies, web browsers, and assistive technology. However, note that techniques, including "sufficient techniques", are not automatically accessibility supported. The evaluator is responsible for the accuracy of the assessment of accessibility support and the resulting evaluation.
Methodology Requirement 4.c: Where possible, use techniques and failures (that have been documented by W3C and others as satisfying the Success Criteria) to help assess successes and failures in satisfying the WCAG 2.0 Success Criteria relevant per Step 1.b: Define the Conformance Target (Optional).
Reminder: Techniques and failures in the context of WCAG 2.0 are only informative. They can help assess if WCAG 2.0 Success Criteria are satisfied by providing documented ways of satisfyiing them and commonly occurring failures in meeting them. However, as per the WCAG 2.0 conformance requirements, only the Success Criteria have to be satisfied. And you can use any techniques that satisfy the Success Criteria, whether they are documented yet as part of WCAG 2.0 or not.
The initial sets or sources of techniques and failures to be used during evaluation may be defined in Step 1.c: Define the Techniques and Failures to be Used (Optional). However, during evaluation initial sets may often need to be refined according to the particular situation, such as for evaluating particular web technologies and accessibility features that are identified on the website.
Techniques in the context of WCAG 2.0 are documented ways for satisfying or for going beyond what is required by individual WCAG 2.0 Success Criteria. A WCAG 2.0 Success Criterion is satisfied on a web page when:
Conversely, failures in the context of WCAG 2.0 are documented ways of not satisfying individual WCAG 2.0 Success Criteria. A WCAG 2.0 Success Criterion is not satisfied on a web page when a failure applies to any instance of web content that is addressed by the WCAG 2.0 Success Criterion.
Techniques are not the only way to satisfy WCAG 2.0 Success Criteria, and failures are not the only way to fail WCAG 2.0 Success Criteria. Techniques and failures are not exhaustive as they cannot cover every possible situation. Also, the techniques used to satisfy WCAG 2.0 Success Criteria during the development may not be known to the evaluator. Particularly for newly released web technologies, or when these web technologies are used in particular contexts, there may be no publicly or proprietary documented techniques and failures available to the evaluator. The evaluator has to consider these limitations when using techniques and failures to evaluate conformance to WCAG 2.0.
[For Review: This addresses comment 72, comment 73 and comment 74 (No change). Comment 74 is also addressed in step 4.a.]
Methodology Requirement 4.d: Archive every evaluated web page for reference. (Optional)
[For Review: Changed first sentence to address comment 75. This should make it clear that optional only relates to the extra things. It now points to step 5 for requirements about how to report the evaluation findings.]
Archive web pages for future reference. Please read Step 5 for requirements about how to report the evaluation findings. These can be complemented, to avoid ambiguity, with any of the following as appropriate:
Methodology Requirement 4.e: Record the web accessibility evaluation tools, web browsers, assistive technologies, other software, and methods used to evaluate the web pages. (Optional).
For future reference, record software tools and methods used to evaluate the web pages. This includes versions of web accessibility evaluation tools, web browsers and add-ons, assistive technology, and other software used during the evaluation. Depending on the desired level of detail for reporting (if more than the minimum required) defined by Step 1.d: Define Additional Requirements for Evaluation (Optional), this recording may apply globally for the entire evaluation, to individual web pages, or to individual checks carried out within the audited web pages. For detailed reporting a table or grid may be useful to record what was used for the different pages and Success Criteria in the sample.
[For Review: This addresses comment 76 (no change).]
Methodology Requirement 5: Document the evaluation findings according to Methodology Requirement 5.a and optionally Methodology Requirement 5.b, Methodology Requirement 5.c, and Methodology Requirement 5.d.
[For review: This section describes the minimum requirements for reporting. There can be additional requirements added by the evaluation commissioner, but they are not required by WCAG-EM. In this section, we can indicate where this extra information can be reported (todo). Additional requirements have been discussed on mailing list and in telco 18 July and make the methodology more flexible for people who want to do more. Please review.]
This section describes how to report the evaluation findings that have been gathered during the previous steps. Reporting is a key element of every evaluation and helps facilitate replicability of the results.
Note: Individual pieces of the reporting are gathered throughout the evaluation process, not necessarily at the end of it.
Methodology Requirement 5.a: Document each outcome of the steps defined in Step 1: Define the Evaluation Scope, Step 2: Explore the Target Website, Step 3: Select a Representative Sample, and Step 4: Audit the Selected Sample.
Document the outcomes of each of the previous steps defined in Step 1: Define the Evaluation Scope, Step 2: Explore the Target Website, Step 3: Select a Representative Sample, and Step 4: Audit the Selected Sample, to ensure justifiable, transparent, and repeatable evaluation results. In particular, this includes documenting:
[Editor Note: Reading this, and then Appendix C, the reference to this information in Appendix C is to minimal. It should be more clearly spelled out in the appendix.]
Documentation of the outcome of auditing the representative sample has to include at least the following information for the WCAG 2.0 Succes Criteria:
Besides the minimum requirements of WCAG-EM, evaluation commissioners may require additional detail as per Step 1.d: Define Additional Requirements for Evaluation (Optional). Additions could be: Capturing the successes and failures for every Success Criterium in meeting WCAG 2.0 for each web page. For instance, if an evaluation commissioner wants to give the report to different people for repair work, this requires more detail than minimally required by WCAG-EM. Additional requirements could also include adding use-cases or asking for possible solutions for the failures that were found during the conformance evaluation. It could also be interesting for the target audience of the report to consider adding a section explaining the consequences of the success criteria for users. An optional example report is provided in Appendix C: Example Report.
Note: While such a report is required for conformance with this methodology, it is not required for any parts of this report to be made public unless an optional public accessibility conformance evaluation statement is provided per Step 5.b: Provide a Conformance Evaluation Statement (optional) in which case the minimum evaluation information to be made public is as per the requirements for WCAG 2.0 conformance claims (see Step 5.b: Provide a Conformance Evaluation Statement). In other situations, the level of confidentiality for evaluation reports is usually determined by the evaluation commissioner.
Methodology Requirement 5.b: Provide an accessibility conformance evaluation statement (Optional).
WCAG 2.0 conformance claims can only be made for the web pages that have been actually evaluated and identified to conform with its conformance requirements. WCAG-EM Accessibility conformance evaluation statements for entire websites can be made according to this methodology when:
As per the requirements for WCAG 2.0 conformance claims, accessibility conformance evaluation statements also have to include the following information:
Accessibility conformance evaluation statements can also be made when only partial conformance has been achieved according to the requirements defined in third-party content and lack of accessibility support due to language. In such cases the accessibility conformance evaluation statements have to also include information to identify the following:
Note: It is not possible to make an accessibility conformance evaluation statement for a website that is still in development. Also, in case of a sample, the WCAG-EM Accessibility Conformance Evaluation Statement only shows the extent to which a website 'likely' conforms because it is always possible that there are errors on pages that are within the scope, but that are not selected in the sample.
[Editor Note: In this section we can also address the notion of "reasonable confidence" that is introduced in the introduction of section 3. And provide the relationship to the likely used here. It should be linked to the section about sampling. Also we want to have a closer look at the word conformance (take the word out). This is discussed in the survey 11]
Methodology Requirement 5.c: Provide a performance score. (Optional).
[Editor Note: This is still under discussion. In minutes of 25 August and 29 August telco and also in the 19 september telco. Input for calculating a score can be found at http://www.w3.org/TR/accessibility-metrics-report/ and other places. See minutes. Added "(performance scores are not very useful for inter-site comparisons)" and changed "websites" to "website" (singular).]
[For Discussion: There are a number of comments relevant for this section: comment 84, comment 85, comment 86, comment 87, comment 88, comment 89 and comment 90.]
Performance scores can provide more granular measure for the level of conformance of a website than the WCAG 2.0 conformance levels provide. This can be useful to monitor the progress of a website over time (performance scores are not very useful for inter-site comparisons). However, scores alone do not provide sufficient context and information to understand the actual accessibility state of a website. In some situation such scores can also be misleading as they can be subjective towards certain kinds of web content.
Performance scores as provided in this methodology require that the evaluation is carried out in conformance with this Methodology. They are intended to be supplementary information to evaluation reports and not to be used separately. The type of scoring system used has to be indicated along with the score whenever such a score is provided.
Currently the following scoring approaches are provided by this methodology:
This score calculates a ratio over the entire website. It is a simple approach to determine overall conformance but also very sensitive towards conformance failures. For example, any failure to satisfy a Success Criterion on any web page is directly reflected as failure of the website to satisfy the respective Success Criterion.
This score is calculated as follows:
This score calculates an average ratio over each web page. It is less sensitive to conformance failures such as occassional oversight but does not consider the relative frequency of failures. For example, a website that has relatively few videos but consistenly fails to provide captions for these videos may still have a high score even though it is profoundly disadvantaging certain users.
This score is calculated as follows:
This score calculates an average ratio over all Success Criteria instances. It is least sensitive to conformance failures such as occassional oversight and considers the relative frequency of failures. However, this score is quite demanding to calculate without appropriate tools support. It is also not always easy to determine each possible instance for Success Criteria.
This score is calculated as follows:
Note: According to WCAG 2.0, Success Criteria that do not apply to the content are deemed to have been satisfied. Also, all Success Criteria are not satisfied for web pages on which any of the WCAG 2.0 conformance requirements are not satisfied.
Methodology Requirement 5.d: Provide machine-readable reports. (Optional).
Machine-readable reports facilitate processing the results by authoring and evaluation tools, for example to help monitor accessibility of a website over time. The Evaluation and Report Language (EARL) is a machine-readable format that was specifically designed for this purpose. It is recommended to use EARL for providing machine-readable reports. See also Understanding Metadata to learn more about uses of metadata, including machine-readable reports, such as EARL.
Past and present active participants of the WCAG 2.0 Evaluation Methodology Task Force (Eval TF) include: Shadi Abou-Zahra; Frederick Boland; Denis Boudreau; Amy Chen; Vivienne Conway; Bim Egan; Michael Elledge; Wilco Fiers; Detlev Fischer; Elizabeth Fong; Vincent François; Alistair Garrison; Emmanuelle Gutiérrez y Restrepo; Katie Haritos-Shea; Martijn Houtepen; Peter Korn; Maureen Kraft; Aurelien Levy; David MacDonald; Kerstin Probiesch; Donald Raikes; Corominas Ramon; Roberto Scano; Samuel Sirois; Sarah J Swierenga; Eric Velleman; Konstantinos Votis; Kathleen Wahlbin; Elle Waters; Richard Warren; Léonie Watson.
[For review: Rewrite to be better aligned with the guidance in Step 5: Report the Evaluation Findings. Please review. This rewrite also addresses comment 91.]
This Appendix proposes a minimal level of reporting following the goals defined in Step 1.c: Define the Conformance Target and the documentation defined in Step 5.a: Provide Documentation for Each Step:
Reports could also indicate the impact of issues found and specifically identify any high impact issues that are easy to fix. This could include: Any accessibility issues that interfere with the user completing tasks, issues that affect navigation and orientation, issues that occur very frequently and issues that can cause any loss or harm to a user. A lot of the important but technical information could be put in an appendix (such as documentation of each outcome of the steps as per Step 5.a: Provide Documentation for Each Step).
Changes since the Public Working Draft of 26 February 2013 include:
A full disposition of comments of all the comments received on the 26 February Working Draft is available.