Web accessibility is one facet of Web quality in use, and one of the main actors upon which the success of a Web site depends. In spite of these facts, surveys repeatedly show that the accessibility at the Web for people with disabilities is disappointingly low. At the Web, most pages present many kinds of accessible barriers for people with disabilities. The former scenario encouraged research communities and organizations to develop a large range of approaches to support Web accessibility. Currently, there are so many approaches available that comparisons have emerged to clarify their intent and effectiveness. With this situation in mind, this chapter will discuss the importance of Web accessibility assessment and compare 15 different approaches found in literature. To do so, we provide an evaluation framework, WAAM, and instantiate them by classifying the different proposals. The aim of WAAM is to clarify from an evaluation and classification perspective the situation at the accessibility arena.
Key Terms in this Chapter
True Problem: An accessibility barrier detected by a test.
False Positive: An issue detected by a test that after a manual evaluation it is not consider an accessibility barrier.
Screen Readers: Special applications that vocalize the onscreen data. Pages are typically read from the top left to the bottom right, line by line, one word at a time.
Potential Problem: A possible accessibility barrier detected by a test that requires manual evaluation to identify if it is an accessibility barrier or not.
Annotation: “A remark attached to a particular portion of a document, and covers a broad range in literature… Web annotation is crucial for providing not only human-readable remarks, but also machine-understandable descriptions, and has a number of applications such as discovery, qualification, and adaptation of Web documents” (Hori, Ono, Abe, & Koyanagi, 2004, p. 2).
Evaluation and Reporting Language (EARL): A general-purpose language developed by the W3C for expressing test results.
Accessible Barrier: Is any condition that makes it difficult for people to achieve a goal when they are using a Web site through specified assistive technology.
Travel Objects: The environmental features or elements that travelers use or may need to use to make a successful journey (Yesilada, 2003).
Transcoder: A Web-server system that produces, on fly, a transformed version of a Web page requested by a user or a browser (Brajnik, 2005).
Issue: “An instance of a potential problem detected by a test” (Brajnik, 2004, p. 257).