Nádia Fernandes

On web accessibility evaluation environments

Modern Web sites leverage several techniques (e.g. DOM manipulation) that allow for the injection of new content into their Web pages (e.g., AJAX), as well as manipulation of the HTML DOM tree. This has the consequence that the Web pages that are presented to users (i.e., browser environment) are different from the original structure and content that is transmitted through HTTP communication (i.e., command line environment). This poses a series of challenges for Web accessibility evaluation, especially on automated evaluation software. This paper details an experimental study designed to understand the differences posed by accessibility evaluation in the Web browser. For that, we implemented a Javascript-based evaluator, QualWeb, that can perform WCAG 2.0 based accessibility evaluations in both browser and command line environments. Our study shows that, in fact, there are deep differences between the HTML DOM tree in both environments, which has the consequence of having distinct evaluation results. Furthermore, we discovered that, for the WCAG 2.0 success criteria evaluation procedures we implemented, 67% of them yield false negative answers on their applicability within the command line environment, whereas more than 13% of them are false positives. We discuss the impact of these results in the light of the potential problems that these differences can pose to designers and developers that use accessibility evaluators that function on command line environments.

Evaluating the accessibility of rich internet applications

The Web has been growing in size and complexity and is used for the most diverse activities in our every day life, becoming almost indispensable. Besides, Web applications are becoming more popular, and consequently used by a wide range of people. Thus, it is important to evaluate the accessibility of the new Rich Internet Applications (RIA) to guarantee that everyone can access the information. Currently, there are some tools to evaluate the accessibility of classical Web pages, which use WCAG guidelines. However, Web applications impose different challenges, so it is mandatory to find a way to automatically obtain the dynamically introduced HTML code, in order to evaluate what users really experience. This paper details a new process of accessibility evaluation of Web applications, which evaluates the content by triggering possible events that partially change the Web page. It also presents an experimental study with several Web applications, demonstrating the potential of this framework in evaluating Web applications.

Three web accessibility evaluation perspectives for RIA

With the increasing popularity of Rich Internet Applications (RIAs), several challenges arise in the area of web accessibility evaluation. A particular set of challenges emerges from RIAs dynamic nature: original static Web specifications can change dramatically before being presented to the end user; a user triggered event may provide complete new content within the same RIA. Whatever the evaluation alternative, the challenges must be met. We focus on automatic evaluation using the current WGAG standards. That enables us to do extensive evaluations in order to grasp the accessibility state of the web eventually pointing new direction for improvement. In this paper, we present a comparative study to understand the difference of the accessibility properties of the Web regarding three different evaluation perspectives: 1) before browser processing; 2) after browser processing (dynamic loading); 3) and, also after browser processing, considering the triggering of user interaction events. The results clearly show that for a RIA the number of accessibility outcomes varies considerably between those tree perspectives. First of all, this variation shows an increase of the number of assessed elements as well as passes, warnings and errors from perspective 1 to 2, due to dynamically loaded code, and from 2 to 3, due to the new pages reached by the interaction events. This shows that evaluating RIAs without considering its dynamic components provides an erroneous perception of its accessibility. Secondly, the relative growth of the number of fails is bigger than the growth of passes. This signifies that considering pages reached by interaction reveals lower quality for RIAs. Finally, a tendency is shown for the RIAs with higher number of states also exposing differences in accessibility quality.

An analysis of personalized web accessibility

This paper presents an experimental study designed to understand the differences of performing personalized Web accessibility evaluations or generic evaluations. We used the WaaT evaluator, which can perform personalized WCAG 2.0 based evaluation. We claim that these tools can be used by an individual to understand if a page is accessible to himself, before wasting time browsing its content. Our study shows that there are considerable differences between the generic and the personalized evaluation results. It also shows that the number of barriers found in accessing pages is in average considerably lower for users with upper limb and cognitive impairments than for those with vision and hearing impairments. Finally, we argue that common accessibility evaluation metrics are inadequate to understand the differences between these user perspectives of the same page. For a particular metric, we show that score differences are diminished and sometimes even mislead the perception of the accessibility quality.

Web Accessibility in Africa: A Study of Three African Domains

Being the most used method for dissemination of information, especially for public services, it is of paramount importance that the Web is made accessible as to allow all its users to access the content of its pages.

A macroscopic web accessibility evaluation at different processing phases

This paper details a comparative experimental study to understand the difference of the Webs accessibility properties regarding two different evaluation approaches: using WCAG 2.0 techniques and targeting the pages as they reach the browser; using WCAG 2.0, but evaluating the pages after the browser processing, thus as they will be delivered to the end-user. For that, we evaluated over 20000 Web pages using already established accessibility metrics. We then compared the results obtained from the WCAG 2.0 evaluation of the two processing phases. We observed some changes in the macroscopic properties of the evaluation. Regarding the comparison between the two phases, we observed a narrower distribution of quality, i.e., the worst pages are in fact not that bad, and the best ones not that good.

Evaluating the Accessibility of Web Applications

Abstract The Web has been growing in size and complexity and is used for the most diverse activities in our everyday life, becoming almost indispensable. Besides, Web applications are becoming more popular, and consequently used by a wide range of people. Thus, it is important to evaluate the accessibility of those applications to guarantee that everyone can access the information. Currently, there are some tools to evaluate the accessibility of classical Web pages, which use WCAG guidelines. However, Web applications impose different challenges, so it is mandatory to find a way to automatically obtain the dynamically introduced HTML code, in order to evaluate what users really experience. This paper details a new process of accessibility evaluation of Web applications, which evaluates the content by triggering possible events that partially change the Web page. It also presents an experimental study with several Web applications, demonstrating the potential of this framework in evaluating Web applications.

Evaluating the Accessibility of Adaptive TV Based Web Applications

The accessibility evaluation of Web applications has been gaining momentum in previous years. Several guidelines and systems are now available to assess the accessibility of a Web page. However, these guidelines have been show to be inadequate when assessing dynamic Web applications. Furthermore, when considering adaptive Web applications, another layer of dynamism is introduced, further complication the problem. This chapter presents a framework for accessibility evaluation of adaptive Web applications, expanding on previous work for evaluating dynamic Web applications. The framework will be described in the context of an evaluation of TV based Web applications, and the results will assist in the characterization of the accessibility of this particular field of Web applications.

Evaluating Web accessibility at different processing phases

Modern Web sites use several techniques (e.g. DOM manipulation) that allow for the injection of new content into their Web pages (e.g. AJAX), as well as manipulation of the HTML DOM tree. This has the consequence that the Web pages that are presented to users (i.e. after browser processing) are different from the original structure and content that is transmitted through HTTP communication (i.e. after browser processing). This poses a series of challenges for Web accessibility evaluation, especially on automated evaluation software. This article details an experimental study designed to understand the differences posed by accessibility evaluation after Web browser processing. We implemented a Javascript-based evaluator, QualWeb, that can perform WCAG 2.0 based accessibility evaluations in the two phases of browser processing. Our study shows that, in fact, there are considerable differences between the HTML DOM trees in both phases, which have the consequence of having distinct evaluation results. We discuss the impact of these results in the light of the potential problems that these differences can pose to designers and developers that use accessibility evaluators that function before browser processing.

Accessibility of dynamic adaptive web TV applications

In the last years, TVs have become platforms providing content and entertainment services, such as video on demand, interactive advertising or so-cial networking. Often, these services are Web based applications that run of connected TVs or set-top boxes. Given TVs wide reach, it is paramount TV applications are designed so that information can be perceived by everyone, i.e. should be accessible. These applications increasingly present dynamic aspects, which have been rendering traditional Web evaluation approaches obsolete. Additionally, TV based interaction has specificities that Web based evaluation is unable to cope with. In this paper, we present an automated accessibility evaluation framework to address these challenges. It is based on WCAG 2.0 and Digital TV guidelines. It supports evaluation of the code after browser processing and scanning the whole set of application states. It is capable of evaluating user interface adaptation based on selected user profiles. The paper also presents the evaluation results of three TV based applications according to the proposed framework, which allow a comparison of results of pre and post browser processing as well as pre and post adaptation.