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Abstract

This document provides guidance on evaluating how well websites conform to the Web Content Accessibility Guidelines (WCAG) 2.0. It describes a procedure to evaluate websites and includes considerations to guide evaluators and to promote good practice. It does not provide instructions for evaluating web content feature by feature, which is addressed by the WCAG 2.0 techniques layer. This document is one of a series of informative W3C/WAI resources about Evaluating Websites for Accessibility that complements the 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 primarily intended for people who are experienced in evaluating accessibility using WCAG 2.0 and its supporting resources. It is primarily designed for evaluating existing websites, for example to learn about them and to monitor their level of accessibility. It can also be useful during earlier development stages of websites. It applies to static and dynamically generated websites, mobile websites and applications, and other types of websites. It does not specify particular web technologies, evaluation tools, web browsers, assistive technologies, or other software to use for evaluation. 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.]

Status of this document

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 29 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.

Table of Contents

Overview

List of Sections

List of Appendices

Introduction

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, responsive, 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 grey-box testing), and the main purpose for the evaluation (e.g. to issue an accessibility statement, to plan a redesign process, to perform 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 that evaluators to apply these steps in the context of a particular website. Following this methodology will help evaluators to apply good practice, avoid commonly made 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 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.]

Purposes for this Methodology

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. This methodology is designed for anyone who wants to follow a common procedure for evaluating the conformance 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.]

Relation to WCAG 2.0 Conformance Claims

WCAG 2.0 defines conformance requirements for individual web pages that are known to satisfy each conformance requirement, rather than for entire websites. It also defines how optional conformance claims 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. This is applicable when all web pages that are in the scope of a conformance claim have each been 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 uses of this methodology only a sample of web pages and functionality from a website is selected for evaluation. Thus in the majority of situations, using this methodology alone does not result into WCAG 2.0 conformance claims for the target websites. Guidance on making statements about the outcomes from using this methodology is provided in Step 5.c: Provide an Evaluation Statement (Optional).

[For Review: New section that addresses discussion during telco of 25 July, telco of 12 September, telco of 17 October, and comment 81.]

Background Reading

The information below related to web accessibility essentials, evaluation, and WCAG 2.0 is important for using this methodology:

Web Accessibility Essentials

The following documents introduce the essential components of web accessibility and explain how people with disabilities use the Web. They are critical for understanding the broader context of web accessibility evaluation:

Evaluating Websites for Accessibility

These are particularly important resources that outline different approaches for evaluating websites for accessibility:

Web Content Accessibility Guidelines (WCAG) 2.0

This is the internationally recognized standard explaining how to make web content more accessible to people with disabilities. The following resources are particularly important for accessibility evaluation of websites:

Terms and Definitions

For the purposes of this document, the following terms and definitions apply:

Complete Processes
From WCAG 2.0 Conformance Requirement for Complete Processes:
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.)
Conformance
From WCAG 2.0 definition for "conformance":
Satisfying all the requirements of a given standard, guideline or specification
Core Functionality
Functionality of a website that, if removed, fundamentally changes the use or purpose of the website for users. This includes information that users of a website refer to and tasks that they carry out to perform this functionality.
Note: Examples of functionality include "selecting and purchasing a product from the shop area of the website", "filling and submitting the form provided on the website", and "registering for an account on the website".
Note: Other functionality is not excluded from the scope of evaluation. The term "core functionality" is intended to help identify critical web pages and include them among others in an evaluation.
Common Web Pages
Web pages that are relevant to the entire website. This includes the homepage, login page, and other entry pages, and, where applicable, the sitemap, contacts page, site help, legal information, and similar web pages that are typically linked from all other web pages (usually from the header, footer, or navigation menu of a web page). Common web pages may also be web page states in web applications.
Evaluator
The person, team of people, organization, in-house department, or other entity responsible for carrying out the evaluation.
Evaluation Commissioner
The person, team of people, organization, in-house department, or other entity that commissioned the evaluation.
Note: In many cases the evaluation commissioner may be the website owner or website developer, in other cases it may be another entity such as a procurer or an accessibility monitoring survey.
Relied Upon (Technologies)
From WCAG 2.0 definition for "relied upon":
The content would not conform if that technology is turned off or is not supported
Templates
From ATAG 2.0 definition for "templates":
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.
[Editor Note: This definition is from the 7 November 2013 Candidate Recommendation (CR) Working Draft of ATAG 2.0. While this is a stable Working Draft, this definition might change in future drafts depending on how ATAG 2.0 evolves.]
Website
A coherent collection of one or more related web pages that together provide common use or functionality. It includes static web pages, dynamically generated web pages, and mobile websites and applications.
Note: The focus of this methodology is on full, self-enclosed websites. Websites may be composed of smaller sub-sites, each of which can be considered to be an individual website. For example, a website may include an online shop, an area for each department within the organization, a blog area, and other areas that may each be considered to be a website.
Website Developer
The person, team of people, organization, in-house department, or other entity that is involved in the website development process including but not limited to content authors, designers, programmers, quality assurance testers, and project managers.
Website Owner
The person, team of people, organization, in-house department, or other entity that is responsible for the website.
Web Page
From WCAG 2.0 definition for "web page":
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
Note: Web pages may include multimedia content, interactive components, and rich and mobile web applications.
Web Page States
[For review: Added this new definition, also to address Comment 13.]
Web pages with dynamic content can have different states; for example, they might generate different content and provide different presentation or functionality depending on the particular user and on actions initiated by the user. Some web page states are ancilliary or treated similarly to individual web pages in the context of this methodology.
Note: Examples of web page states are the individual pages of a multi-part online form that are dynamically generated depending on users input. These individual states may not have unique URIs and may need to be identified by describing the settings, input, and actions required to generate them.

Using This Methodology

This methodology is used for thorough evaluation of websites with WCAG 2.0. Before evaluating an entire website it is usually good to do a preliminary evaluation of different web pages from the target website to identify obvious accessibility barriers and 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.

Required Expertise

Users of this methodology 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 relevant web technologies, accessibility barriers that people with disabilities experience, assistive technologies and approaches that people with disabilities use, and evaluation techniques, tools, and methods to identify potential barriers for people with disabilities. In particular, it is assumed that users of this methodology are deeply familiar with the resources listed in section Background Reading.

Evaluation Tools (Optional)

This methodology 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.

Review Teams (Optional)

This methodology can be carried out by an individual evaluator with the skills described in the section Required Expertise. However, using the combined expertise of review teams provides broader coverage of the required skills and helps identify accessibility barriers more effectively. While not required for using this methodology, the use of review teams is highly recommended when performing an evaluation of a website. Using Combined Expertise to Evaluate Web Accessibility provides further guidance beyond the scope of this document.

Involving Users (Optional)

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 that evaluators 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.

Scope of Applicability

This methodology is designed for evaluating full, self-enclosed websites. This includes websites of organizations, entities, persons, events, products, and services.

Examples of Websites

Specific examples of websites include:

A website can be part of a larger website, such as the online shop in the preceding examples. A website can also be a clearly separable version of the website such as the mobile or Dutch language versions of the website, as shown in the preceding examples. This methodology can be applied to any such determinable website, regardless whether or not it is part of a larger website. The exact definition of a target website to be evaluated is determined as part of Step 1.a.

Principle of Website Enclosure

When a target website is defined for evaluation, it is essential that all web pages, web page states, and functionality within the scope of this definition are considered for evaluation. Excluding such aspects of a website from the scope of evaluation would likely conflict with the WCAG 2.0 conformance requirements for full pages and complete processes, or otherwise distort the evaluation results.

Example of Website Enclosure

Diagram of a University Website explained in the following paragraph.

The preceding diagram shows a university website comprised of 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. The university website also has individual web pages such as legal notices, sitemap, and other web pages that are common to all areas.

In the preceding example, 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. If only a specific 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, the scope of evaluation would include all depicted courses, as well as the individual web pages that are common to all areas of the university. See also the definition for Common Web Pages.

Particular Types of Websites

This methodology is applicable to the broad variety of websites. The following considerations apply to particular types of websites:

Small Websites
For websites with few web pages the sampling procedure defined in Step 3: Select a Representative Sample will likely result in selecting most or all of the web pages from the target website. In cases where all web pages can be evaluated, the sampling procedure can be skipped and the selected sample is considered to be the entire website in the remaining steps.
Web Applications
Web applications are generally composed of dynamically generated content and functionality (see web page states). Web applications tend to be more complex and interactive. Some examples of web applications include webmail clients, document editors, and online shops. Web applications may be part of a larger website but can also constitute a website of their own in the context of this methodology. That is, an individual and separable entity for evaluation.
Note: Due to the many possibilities of generating content and functionality in web applications it is sometimes not feasible to exhaustively identify every possible web page, web page state, and functionality. Web applications will typically require more time and effort to evaluate, and larger web page samples to reflect the different types of content, functionality, and processes.
Website with Separable Areas
In some cases websites may have clearly separable areas where using one area does not require or depend on using another area of the website. For example, an organization might provide an extranet for its employees only that is linked from the public website but is otherwise separate, or it might have sub-sites for individual departments of the organization that are each clearly distinct from one another. Such separable areas can be considered as individual websites each for evaluation. In some cases there may be common web pages, such as legal notices, that need to be considered as part of each website area.
Note: Some websites provide additional or different content and functionality depending on the user (typically after a log-in). This additional content and functionality is generally part of the core purpose and functionality of the website and is thus not considered to be a separable website area.
Website in Multiple Versions
Some websites are available in multiple versions that are each independent of one another in usage, where using one version does not require or depend on using another version of the website. For example, a website may have a mobile version and there may be versions of a website in different languages that meet this characteristic. Usually each such website version has a different set of URIs. Such website versions can be considered as individual websites for evaluation.
Note: Websites using responsive design techniques (i.e. adapting the presentation according to user hardware, software, and preferences) as opposed to redirecting the user to a different location are not considered to be independent website versions.

Particular Evaluation Contexts

This methodology is designed to be flexible to facilitate its applicability in different situations and contexts. The following considerations apply to particular situations and contexts for an evaluation:

Self-Assessment of Conformance
In this context evaluators often have easier access to the website developers and maintainers, the development environment and authoring tools, and the materials used for development. Particularly use cases, design analysis, technical specifications and documentation, and testing resources can make evaluation more effective and should be leveraged where possible.
Third-Party Assessment of Conformance
Third-party evaluators typically use pure black-box testing and have little information about how a website was developed and all its areas and functionality. Therefore it is more difficult, often impossible, to make conformance claims based on such an evaluation alone. However, such evaluation can be effective for validating conformance claims and statements about websites.
Evaluating During Development
It is critical to evaluate accessibility throughout the design and implementation stages of a website to manage its conformance. This methodology provides guidance that can be useful during these earlier stages of the development process, though some adaptation may be needed. However, it is important to be aware that evaluations carried out during these development stages can quickly become obsolete by implementing even minor changes. Consequently evaluations carried out during these stages should not be used for making statements nor conformance claims about the finalized website.
Evaluating Composite Websites
When evaluating websites that are composed of separable areas, such as online shop, blog area, and other sub-sites, it can be useful to first evaluate each website area separately according to this methodology, followed by an overall evaluation with samples from each website area and any common web pages. This would ensure more complete coverage of the website in its entirety as well as provide insights about how each website area performed, which may differ from one area to another.
Evaluating Aggregated Websites
Websites that are generated using content that is combined from different sources, such as portals with portlets, are usually much more challenging to evaluate because of the many different content instances that can be generated. Generally it is not possible to evaluate the content from their sources separately but rather as displayed to the users when they are combined.
Evaluating Third-Party Content
Third-party content is not under the control of the website or web service providers; for example content generated by website users in an online forum. When such content is regularly monitored and repaired (within two business days), then the content can be deemed as conforming according to WCAG 2.0. Otherwise the non-conforming content needs to be clearly identified in the web pages in which it appears. WCAG 2.0 provides more guidance on providing a Statement of Partial Conformance.
Re-Running Website Evaluation

Website 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 barriers that were identified, include at least:

Large-Scale Evaluation
Carrying out mass evaluation of many websites, for example for national or international surveying, is typically carried out using primarily automated evaluation tools. Relatively few web pages undergo full manual inspection. Such evaluations do not usually address the necessary qualitative depth of review per website for which this methodology is primarily designed.

Evaluation Procedure

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:

Diagram about the iterations between the steps in this methodology. Explanation in the following paragraph.

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 findings.

Note: See also considerations for Particular Evaluation Contexts that may influence how an evaluation procedure is carried out.

Step 1: Define the Evaluation Scope

Methodology Requirement 1: Define the evaluation scope according to Methodology Requirement 1.a, Methodology Requirement 1.b, and Methodology Requirement 1.c, and optionally Methodology Requirement 1.d and Methodology Requirement 1.e.

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. It is ideally carried out in consultation with the evaluation commissioner (who may or may not be the website owner) to ensure common expectations about the scope of the evaluation. Initial exploration of the target website during this stage may be necessary to better know specifics of the website and the required evaluation (see Step 2: Explore the Target Website).

Step 1.a: Define the Scope of the 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 defined. This scope of the website is defined according to the terms established in the 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. Using formalizations including regular expressions and listings of web addresses (URIs) is 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).]

Step 1.b: Define the Conformance Target

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.

Step 1.c: Define an Accessibility Support Baseline

Methodology Requirement 1.c: Define the web browser, assistive technologies and other user agents for which features provided on the website are to be accessibility supported.

Particularly for new web technologies it is usually not possible that every accessibility feature, such as a 'show captions' function in a media player, is supported by every possible combination of web browser, assistive technology, and other user agents. WCAG 2.0 does not pre-define which combinations of features and technologies must be supported as this depends on the particular context of the website, including its language, the web technologies that are used to create the content, and the user agents currently available. Understanding Accessibility Support provides more guidance.

During this step a list of web browsers, assistive technologies, and other user agents that support the accessibility features on the website is defined. For some websites in closed networks, such as an intranet website where the computers used to access it are known, this baseline may be limited to the web browsers and assistive technologies used within this closed network. However, in most cases this baseline is ideally as broad as possible to cover the majority of user agents used by people with disabilities.

Step 1.d: Define Evaluation Methods to be Used (Optional)

Methodology Requirement 1.d: Define any initial evaluation methods to be used to help evaluate conformance to WCAG 2.0 Success Criteria (Optional).

Determining conformance to WCAG 2.0 Success Criteria can be typically done in several ways. W3C/WAI provides a set of publicly documented (non-normative) Techniques for WCAG 2.0 that help evaluate conformance to WCAG 2.0 Success Criteria. However, it is not necessary to use these particular techniques (see Understanding Techniques for WCAG Success Criteria). Some evaluators might use other methods (inline with the requirements for custom techniques) to evaluate conformance to WCAG 2.0.

During this step, particular evaluation methods, if any are to be used, are defined. This does not limit the evaluator from using other additional evaluation methods at a later point, for example to evaluate particular content that was not identified at this early stage of the evaluation process. However, it is good practice to specify the initial evaluation methods to be used during the evaluation, as it helps to ensure consistent expectation between the evaluator and the evaluation commissioner.

Step 1.e: Define Additional Evaluation Requirements (Optional)

Methodology Requirement 1.e: 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.

Step 2: Explore the Target Website

Methodology Requirement 2: Explore the website to be evaluated according to Methodology Requirement 2.a, Methodology Requirement 2.b, Methodology Requirement 2.c, Methodology Requirement 2.d, and Methodology Requirement 2.e.

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.

Step 2.a: Identify Common Web Pages of the Website

Methodology Requirement 2.a: Identify the common web pages, including web page states, of the target website.

Explore the target website to identfy its common web pages, which may also be web page states in web applications. 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 and web page states.

Step 2.b: Identify Core Functionality of the Website

Methodology Requirement 2.b: Identify an initial list of core functionality of the target website.

Explore the target website to identify 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.

Step 2.c: Identify the Variety of Web Page Types

Methodology Requirement 2.c: Identify the types of web pages and web page states.

Web pages and web page states with varying styles, layouts, structures, and functionality often have varying support for accessibility. They are also often generated by different templates and scripts, or authored by different people. They may also appear differently, behave differently, and contain different content depending on the particular website user and context. The outcome of this step is a list of the different types (as opposed to specific instances) of web pages and web page states that appear on the target website.

Examples of web page and web page states types include:

Step 2.d: Identify Web Technologies Relied Upon

Methodology Requirement 2.d: Identify the web technologies relied upon to provide the website.

During this step the web technologies relied upon to provide the website are identified. 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.

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.

Step 2.e: Identify Other Relevant Web Pages

Methodology Requirement 3.c: Identify other web pages and web page states that are relevant to people with disabilities and to accessibility of the website.

Some websites include web pages and web page states that are specifically relevant for people with disabilities and accessibility of the website. The outcome of this step is a list of such web pages. This includes:

Step 3: Select a Representative Sample

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, and Methodology Requirement 3.e.

During this step the evaluator selects a sample of web pages and web page states that is representative of the target website to be evaluated. The purpose of this selection is to ensure that the evaluation results reflect the accessibility performance of the website with reasonable confidence. In cases where it is feasible to evaluate all web pages, this sampling procedure can be skipped and the selected sample is considered to be the entire website in the remaining steps of the conformance evaluation procedure.

The actual size of sample web pages and web page states needed to evaluate a website depends on many factors including:

This step relies initially on the exploration carried out in Step 2: Explore the Target Website and is continually refined during the later Step 4: Audit the Selected Sample, as the evaluator learns more about the particular implementation aspects of the target website.

Step 3.a: Include Common Web Pages of the Website

Methodology Requirement 3.a: Include all common web pages, including web page states, into the selected sample.

Include all common web pages and web page states that were identified in Step 2.a: Identify Common Web Pages of the Website into the selected sample for evaluation.

Step 3.b: Include Other Relevant Web Pages

Methodology Requirement 3.b: Include all other web pages and web page states that are relevant to people with disabilities and accessibility of the website into the selected sample.

Include all other relevant web pages and web page states that were identified in Step 2.e: Identify Other Relevant Web Pages into the selected sample for evaluation.

Step 3.c: Include Exemplar Instances of Web Pages

Methodology Requirement 3.c: Include distinct instances of web pages and web page states (where applicable and available) to cover the (1) core functionality, (2) types of web pages, and (3) web technologies relied upon into the selected sample.

Depending on the required sample size (see guidance on sample size earlier in this section), include at least one distinctinstance of web page or web page state matching any of the following into the selected sample for evaluation (where applicable and available):

Note: An individual web page or web page state may reflect more than one of each of these listed criteria. For example, a single web page may be representative of a particular design layout, functionality, and web technologies used. The purpose of this step is to have sufficient representation of the different types of web pages and web page states, functionality, and web technologies that occur on the website. Careful selection of these representative instances can significantly reduce the required sample size while maintaining appropriate representation of the entire website.

Step 3.d: Include Complete Processes in the Sample

Methodology Requirement 3.d: Include all web pages and web page states that are part of a complete process into the selected sample.

The selected sample has to include all web pages and web page states that belong to a series presenting a complete process. No web page or web page state in the selected sample may be part of a process without all other web pages and web page states that are part of that process to be also included into the selected sample.

Use the following steps to include the necessary web pages and web page states into the sample:

  1. For any web page and web page state selected through Step 3.c: Include Exemplar Instances of Web Pages and that is part of a process, locate the starting point (web page or web page state) for the process and replace them in the selected sample;
  2. For each core functionality identified in Step 2.b: Identify Core Functionality of the Website, locate the starting points (web page or web page state) for the processes associated with each functionality and include them into the selected sample;
  3. For each starting point for a process, identify and record at least the default sequence of web pages and web page states to complete the process. Add these web pages and web page states into the selected sample.
    Note: The default sequence follows the standard use case, describing the default path through the complete process. It assumes that there are no user input errors and no selection of additional options. For example, for a web shop application, the user would proceed to checkout, confirm the default payment option, provide all required payment details correctly, and complete the purchase, without changing contents of the shopping cart, using a stored user profile, selecting alternative options for payment or shipping address, providing erroneous input, and so forth.
  4. For each process, identify and record the branch sequences of web pages and web page states that are commonly accessed and critical for the successful completion of the process. Add these web pages and web page states into the selected sample.
    Note: Branch sequences may terminate where they re-enter the default branch of the process. For example, adding a new shipping address will be registered as a critical alternative branch that leads back to the default branch of the process.

Note: In most cases it is necessary to record and specify the actions needed to proceed from one web page and web page state to the next in a sequence to complete a process so that they can be replicated later. An example of such action could be "fill out name and address, and select the 'Submit' button". In most cases the web address (URI will not be sufficient to identify the web page and web page state in a complete process. It is also useful to clearly record when web pages and web page states are part of a process so that evaluators can focus their effort on the relevant changes such as elements that were added, modified, or made visible.

Step 3.e: Include a Randomly Selected Sample

Methodology Requirement 3.e: Select a random sample of web pages and web page states, and include them for auditing.

A randomly selected sample of web pages and web page states acts as an indicator to verify that the structured sample selected through the previous steps truly reflects the accessibility performance of the website. Confidence in the overall evaluation outcome increases when the evaluation results from both selection approachs correlate.

The number of web pages and web page states to randomly select is 10% of the structured sample selected through the previous steps, with a minimum of 5 instances of web pages and web page states. For example, if the structured sample resulted in 80 web pages and web page states, then the random sample size is 8 web pages and web page states. For structured samples of size 50 and below the random sample size is always 5 web pages and web page states (if the website is not smaller than that).

To perform this selection, randomly select unique instances of web pages and web page states from the target website and that are not already part of the structured sample selected through the previous steps. Depending on the type of website and the access that an evaluator has for it there are different techniques that may need to be used for this selection. This may include:

Document the web pages and web page states that were randomly selected as these will need to be compared to the remaining structured sample in Step 4.e: Compare Structured and Random Samples.

Note: While the random sample need not be selected according to strictly scientific criteria, the scope of the selection needs to span the entire scope of the website (any web page and web page state on the website may be selected with similarly equivalent likelihood), and the selection of individual web page and web page states does not follow a predictable pattern. Recording the method used to generate the random sample is important for replicability and reliability of the results.

Step 4: Audit the Selected Sample

Methodology Requirement 4: Audit the selected sample of web pages according to Methodology Requirement 4.a, Methodology Requirement 4.b, Methodology Requirement 4.c, Methodology Requirement 4.d and Methodology Requirement 4.e.

During this step the evaluator audits (detailed evaluation) the sample selected in Step 3: Select a Representative Sample according to the five WCAG 2.0 conformance requirements at the conformance level from Step 1.b: Define the Conformance Target. Many web pages and web page states in the sample will have components, such as the header, navigation bars, search form, and others that are occur repeatedly. Typically these components do not need to be re-evaluated on each occurrence unless the appear or behave differently, or when additional requirements are defined in Step 1.d: Define Additional Requirements for Evaluation (Optional).

Important: Carrying out this step requires deep understanding of the WCAG 2.0 conformance requirements and the WCAG 2.0 Layers of Guidance. Understanding Conformance provides more guidance.

Note: According to WCAG 2.0, Success Criteria to which there is no matching content presented on a web page or web page state are deemed "satisfied". In such cases, an evaluator may use an identifier such as "not applicable" to denote the particular situations where Success Criteria are satisfied because no matching content is presented.

[For Review: This addresses comment 58, comment 59, comment 60, comment 61, comment 62, comment 63 and comment 57 (no change).]

Step 4.a: Check for Each Success Criterion

Methodology Requirement 4.a: Check that each full page (web page and web page state) in the selected sample satisfies each of the WCAG 2.0 Success Criteria of the target conformance level.

For each web page and web page state in the sample selected in Step 3: Select a Representative Sample that is not within or the end of a complete process, check its conformance with each WCAG 2.0 Success Criterion within the target conformance level (as per Step 1.b: Define the Conformance Target). This includes all components of the web page or web page state without activating any functions, entering any data, or otherwise interacting with the content (this will be evaluated in the subsequent steps).

Consider the following approach for evaluating the conformance of all content to each WCAG 2.0 Success Criterion:

Note: W3C/WAI continually documents (non-normative) failures and techniques for WCAG 2.0 but these can never be exhaustive to cover every possible situation. They are also not the only ways to meet or to fail to meet WCAG 2.0 Success Criteria, and evaluators typically use additional methods to evaluate conformance to WCAG 2.0 (see also Step 1.d: Define Evaluation Methods to be Used).

[For Review: Addresses comment 64, comment 65, comment 66, comment 67, comment 68, comment 72, comment 73, and comment 74.]

Step 4.b: Check for Complete Processes

Methodology Requirement 4.b: Check that all interaction of each web page and web page state along a complete process satisfies each of the WCAG 2.0 Success Criteria of the target conformance level.

For each complete process selected in Step 3.d: Include Complete Processes in the Sample, follow the identified default and branch sequences of web pages and web page states, and evaluate each according to Step 4.a: Check WCAG 2.0 Success Criteria. However, in this case it is not necessary to evaluate all content but only the content that changes along the process.

Functionality, entering data, notifications, and other interaction is part of this check. In particular it includes:

Step 4.c: Check for Accessible Alternatives

Methodology Requirement 4.c: Check that each web page and web page state in the selected sample that does not conform to WCAG 2.0 at the target conformance level has a conforming alternate version.

For each of the web pages and web page states in the selected sample (as per Step 3: Select a Representative Sample) that does not satisfy any of the five WCAG 2.0 conformance requirements at the conformance level (as per Step 1.b: Define the Conformance Target), check that it has at least one conforming alternate version as defined per WCAG 2.0. Understanding Conforming Alternate Versions provides more guidance on this WCAG 2.0 requirement.

Step 4.d: Check for Non-Interference

Methodology Requirement 4.d: Check that each web page and web page state in the selected sample satisfies the WCAG 2.0 conformance requirement non-interference.

For each of the web pages and web page states in the selected sample (as per Step 3: Select a Representative Sample), check that it satisfies the WCAG 2.0 conformance requirement non-interference. Understanding Requirement 5 provides more guidance.

Step 4.e: Compare Structured and Random Samples

Methodology Requirement 4.e: Check that each web page and web page state in the randomly selected sample does not show types of content and outcomes that are not represented in the structured sample.

The evaluation outcomes of the structured and random sample correlate when they are sufficiently large and representative. While the individual occurences of WCAG 2.0 Success Criteria will vary between the samples, the randomly selected sample should not show new types of content (as identified in Step 2: Explore the Target Website), and the outcomes from evaluating these randomly selected sample should not show new findings to those that were already determined in the structured sample. When the correlation fails then evaluators need to select additional web pages and web page states (as per Step 3: Select a Representative Sample), to reflect the newly identified types of content and outcomes. The outcomes of Step 2: Explore the Target Website might need to be adjusted accordingly as well. This step is repeated until the structured sample is adequately representative.

Step 5: Record the Evaluation Findings

Methodology Requirement 5: Document the evaluation findings according to Methodology Requirement 5.a and optionally Methodology Requirement 5.b, Methodology Requirement 5.c, Methodology Requirement 5.d, and Methodology Requirement 5.e.

While evaluation findings are reported at the end of the process, recording them is carried out throughout the evaluation process to ensure reliable outcomes. The recordings typically have varying levels of confidentiality. For example, recording the specific methods used to evaluate individual requirements might remain limited to the evaluator while reports about the outcomes from these checks are typically made available to the evaluation commissioner. Website owners might further choose to make public statements about the outcomes from evaluation according to this methodology.

Step 5.a: Document the Outcomes of Each Step

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.

Documenting the outcomes for each of the previous steps (including all sub-sections) is essential to ensure transparency of the evaluation process, replicability of the evaluation results, and justification for any statements made based on this evaluation. This documentation does not need to be public (the level of confidentiality is usually determined by the evaluation commissioner), though it needs to be made available to the evaluation commissioner upon request as it is part of carrying out this methodology.

Documenting the outcomes for each step includes at least the following:

Note: The outcomes of Step 4: Audit the Selected Sample can be aggregated over the entire sample. That is, for every WCAG 2.0 Success Criterion applicable (as per Step 1.b. Define the Conformance Target) and the remaining four WCAG 2.0 conformance requirements, the evaluator indicates whether each is met on every web page and web page state in the selected sample (as per Step 3: Select a Representative Sample), or provides at least one example for each conformance requirement and WCAG 2.0 Success Criterion not met (without having an accessible alternative).

Depending on any additional evaluation requirements established in Step 1.e: Define Additional Evaluation Requirements (Optional) there may be additional evaluation outcomes to report. For example, an evaluation commissioner may request a report indicating every failure occurrence for every web page and web page state in the selected sample, more information about the nature and the causes of the identified failures, or repair suggestions to remedy the failures.

Step 5.b: Record the Evaluation Specifics (Optional)

Methodology Requirement 5.b: Archive the web pages and web page states audited, and record the evaluation tools, web browsers, assistive technologies, other software, and methods used to audit them (Optional).

While optional, it is good practice for evaluators to keep record of the evaluation specifics, for example to support conflict resolution in the case of dispute. This includes archiving the web pages and web page states audited, and recording the evaluation tools, web browsers, assistive technologies, other software, and methods used to audit them. This recording is typically kept internal and not shared by the evaluator unless otherwise agreed on in Step 1.e: Define Additional Evaluation Requirements (Optional).

Records of the evaluation specifics could include any of the following:

This recording may apply globally for the entire evaluation, to individual web pages, or to individual checks carried out within the audited web pages and web page states. A table or grid may be useful to record what was used for the different web pages and web page states audited.

[For Review: This addresses comment 75 and comment 76.]

Step 5.c: Provide an Evaluation Statement (Optional)

Methodology Requirement 5.c: Provide an statement describing the outcomes of the conformance evaluation (Optional).

Reminder: In the majority of situations, using this methodology alone does not result into WCAG 2.0 conformance claims for the target websites; see Relation to WCAG 2.0 Conformance Claims for more background.

Website owners may wish to make public statements about the outcomes from evaluations following this methodology. This can be done when at least every non-optional methodology requirement is satisifed, the conformance target (as per Step 1.b. Define the Conformance Target) is satisfied by all web pages and web page states audited (as per Step 4: Audit the Selected Sample), and the website owner commits to ensuring the validty and maintaining the accuracy of the evaluation statement made.

An evaluation statement according to this methodology includes at least the following information:

  1. Date of when the evaluation statement was issued;
  2. Guidelines title, version and URI: "Web Content Accessibility Guidelines 2.0 at http://www.w3.org/TR/WCAG20/";
  3. Conformance level satisfied: Level A, AA or AAA as per Step 1.b. Define the Conformance Target;
  4. Definition of the website as per Step 1.a: Define the Scope of the Website;
  5. Web technologies relied upon as per Step 2.d: Identify Web Technologies Relied Upon;
  6. Accessibility support baseline as per Step 1.c: Define an Accessibility Support Baseline.

Evaluation statements according to this methodology can also be made when only partial conformance to WCAG 2.0 has been achieved. In such cases the evaluation statements have to also include the following information:

  1. Website areas that do not conform to WCAG 2.0;
  2. Reason for not conforming to WCAG 2.0: "third-party content" or "lack of accessibility support for languages";

Step 5.d: Provide a Performance Score (Optional)

Methodology Requirement 5.d: 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 intended for inter-site comparisons. Performance scores alone also do not provide sufficient context and information to understand the actual accessibility of a website. In some situation such scores can also be misleading and can be subjective towards certain kinds of web content.

Currently the following performance scoring approaches are provided by this methodology:

Per Website

This score calculates a ratio over the entire selected sample. It is a simple approach to indicate the overall performance. It is sensitive towards conformance failures. For example, any failure to satisfy a WCAG 2.0 Success Criterion on any web page or web page state is reflected as a failure of the entire sample to satisfy the respective WCAG 2.0 Success Criterion.

This score is calculated as follows:

  1. List the WCAG 2.0 Success Criteria applicable to the evaluation (as per Step 1.b. Define the Conformance Target).
  2. During the evaluation mark the Success Criteria that are satisfied on all of the web pages and web page states within the selected sample (as per Step 3: Select a Representative Sample). For example, if WCAG 2.0 Success Criterion 1.1.1 is satisfied on all web pages and web page states, then this Success Criterion is marked as satisfied.
  3. After the evaluation, calculate the sum of WCAG 2.0 Success Criteria that are satisfied consistently across the entire sample, and divide this by the sum of all WCAG 2.0 Success Criteria applicable to the evaluation.
Per Web Page

This score calculates an average ratio over each web page and web page state in the selected sample. 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:

  1. List the WCAG 2.0 Success Criteria applicable to the evaluation (as per Step 1.b. Define the Conformance Target).
  2. During the evaluation mark any WCAG 2.0 Success Criteria that are satisfied for each of the web pages and web page states within the selected sample (as per Step 3: Select a Representative Sample). For example, if WCAG 2.0 Success Criterion 1.1.1 is satisfied on a given web page or web page state, then this WCAG 2.0 Success Criterion is marked as "satisfied" for that one web page or web page state.
  3. After the evaluation calculate the entire sum of WCAG 2.0 Success Criteria that are satisfied on each web page and web page state in the sample, and divide this by the sum of all applicable WCAG 2.0 Success Criteria across all web pages and web page states in the selected sample.
Per Instance

This score calculates an average ratio over all WCAG 2.0 Success Criteria occurrences in the selected sample. 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 occurrence of WCAG 2.0 Success Criteria.

This score is calculated as follows:

  1. List the WCAG 2.0 Success Criteria applicable to the evaluation (as per Step 1.b. Define the Conformance Target).
  2. During the evaluation of each web page and web page state within the selected sample (as per Step 3: Select a Representative Sample), calculate the sum of instances for which each WCAG 2.0 Success Criterion is applicable for each web page and web page state, and the number of instances for which they are satisfied. For example, calculate the number of times in which WCAG 2.0 Success Criterion 1.1.1 was applicable on a given web page or web page state, and the number of times in which it was satisfied.
  3. After the evaluation calculate the entire sum of WCAG 2.0 Success Criteria that were satisfied on each web page and web page state, and divide this by the sum of all applicable WCAG 2.0 Success Criteria across all web pages and web page states in the selected sample.

Note: According to WCAG 2.0, Success Criteria that do not apply to the content are deemed to have been satisfied. WCAG 2.0 Success Criteria are not satisfied for web pages on which any of the WCAG 2.0 conformance requirements are not satisfied.

Step 5.e: Provide Machine-Readable Reports (Optional)

Methodology Requirement 5.e: Provide machine-readable reports of the evaluation results (Optional).

Machine-readable reports facilitate processing the evaluation results by authoring, web accessibility evaluation tools, and quality assurance tools. 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 from WCAG 2.0 to learn more about uses of metadata, including machine-readable reports, such as EARL.

Appendix A: Contributors

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; Gavin Evans; 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; Mary-Jo Mueller; 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.

Appendix B: References

QA-FRAMEWORK
Dubost K, Rosenthal L, Hazaël-Massieux D, Henderson L (eds) (2005) W3C Quality Assurance Framework: Specification Guidelines. W3C. Available at: http://www.w3.org/TR/qaframe-spec/
RFC3986
Fielding R, Gettys J, Mogul J, Frystik H, Masinter L, Berners-Lee T (eds) (1999). Hypertext Transfer Protocol - HTTP/1.1. Request for Comments: 2616. IETF. Available at: http://www.ietf.org/rfc/rfc3986.txt
RFC2616
Berners-Lee T, Fielding R, Masinter L (eds) (2005). Uniform Resource Identifier (URI): Generic Syntax. Request for Comments: 3986. IETF. Available at: http://www.ietf.org/rfc/rfc2616.txt
UWEM
Velleman E.M, Velasco C.A, Snaprud M (eds) (2007). D-WAB4 Unified Web Evaluation Methodology (UWEM 1.2 Core). Wabcluster. Available at: http://www.wabcluster.org/uwem1_2/
WCAG20
Caldwell B, Cooper M, Guarino Reid L, Vanderheiden G, eds (2008). Web Content Accessibility Guidelines 2.0. W3C. Available at: http://www.w3.org/TR/WCAG20/

Appendix C: Document Changes

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.