Myriam Arrue

The use of guidelines to automatically verify Web accessibility

Accessibility is one of the key challenges that the Internet must currently face to guarantee universal inclusion. Accessible Web design requires knowledge and experience from the designer, who can be assisted by the use of broadly accepted guidelines. Nevertheless, guideline application may not be obvious, and many designers may lack experience to use them. The difficulty increases because, as the research on accessibility is progressing, existing sets of guidelines are updated and new sets are proposed by diverse institutions. Therefore, the availability of tools to evaluate accessibility, and eventually repair the detected bugs, is crucial. This paper presents a tool, EvalIris, developed to automatically check the accessibility of Websites using sets of guidelines that, by means of a well-defined XML structure, can be easily replaced or updated.

Quantitative metrics for measuring web accessibility

This paper raises the need for quantitative accessibility measurement and proposes three different application scenarios where quantitative accessibility metrics are useful: Quality Assurance within Web Engineering, Information Retrieval and accessibility monitoring. We propose a quantitative metric which is automatically calculated from reports of automatic evaluation tools. In order to prove the reliability of the metric, 15 websites (1363 web pages) are measured based on results yielded by 2 evaluation tools: EvalAccess and LIFT. Statistical analysis of results shows that the metric is dependent on the evaluation tool. However, Spearmans test produces high correlation between results of different tools. Therefore, we conclude that the metric is reliable for ranking purposes in Information Retrieval and accessibility monitoring scenarios and can also be partially applied in a Web Engineering scenario.

Evaluating web accessibility for specific mobile devices

This paper presents a tool for evaluating web accessibility for mobile devices regardless their software, hardware or user agent characteristics. Taking the mobileOK Basic tests by the W3C as a basis, these tests are extended so that device characteristics can be considered in the evaluation process. A sound tool that takes into account these extended tests has been developed. Device features of a given device are retrieved from heterogeneous device description repositories and CC/PP based profiles are automatically generated. Based on these profiles, evaluation queries are dynamically created obtaining device-tailored evaluation reports. Finally, in order to demonstrate the feasibility of the tool, a case study has been conducted concluding that the tool reduces the number of false positives and false negatives.

Including Heterogeneous Web Accessibility Guidelines in the Development Process

The use of web applications has extremely increased in the last few years. However, some groups of users may experience difficulties when accessing them. Many different sets of accessibility guidelines have been developed in order to improve the quality of web interfaces. Some of them are of general purpose whereas others are specific for user, application or access device characteristics. The existing amount of heterogeneous accessibility guidelines makes it difficult to find, select and handle them in the development process. This paper proposes a flexible framework which facilitates and promotes the web accessibility awareness during all the development process. The basis of this framework is the Unified Guidelines Language (UGL), a uniform guidelines specification language developed as a result of a comprehensive study of different sets of guidelines. The main components of the framework are the guidelines management tool and the flexible evaluation module. Therefore, sharing, extending and searching for adequate accessibility guidelines as well as evaluating web accessibility according to different sets of guidelines become simpler tasks.

Transition of accessibility evaluation tools to new standards

While automatic tools are not intended to replace human judgement they are crucial in order to develop accessible web sites. The release of WCAG 2.0 entails that the existing plethora of accessibility review tools will have to be updated. This paper presents an evaluation framework for making the transition from WCAG 1.0 to WCAG 2.0 in a less painful way. A framework is thus proposed that allows developers to create new guidelines, and update or reuse the existing ones. A case study to test its feasibility has been carried out by incorporating WCAG 2.0 guidelines into the framework. The results are satisfactory, since 55% of the automatic and 16% of the semi-automatic ones could be expressed using the framework. Therefore, it is demonstrated that even if the framework does not fully support the transition process, at least it makes it less burdensome. Moreover, by analyzing WCAG 2.0 we have learnt how to extend the existing tools in order to provide greater coverage and thus increase their effectiveness.

An Expert-Based Usability Evaluation of the EvalAccess Web Service

The activities developed by means of Internet have rapidly increased in the last years. Most of the Internet success is due to the proliferation and popularization of the information and services provided through web sites. However, many web pages have been designed without having in mind that there may be people, devices and even browsers that can not access them. A number of initiatives have been developed to prevent web accessibility barriers, including the accessibility laws promulgated by diverse countries-such as the Section 508 in the USA-. There are also independent institutions that have compiled accessible design guidelines, some of them with great influence in the design of accessible web pages. In particular, the best known ones are the guidelines compiled by the Web Accessibility Initiative (WAI), which is part of the Web Worldwide Consortium (W3C) [1]. All these initiatives specify and regulate the characteristics that universal accessible web sites must have. However, these efforts are not enough if the developers are not provided with tools that support universal design. EvalAccess1 is a tool that automatically evaluates the accessibility of web pages. It is an evolution of the EvalIRIS tool that was developed within IRIS European project [2]. EvalAccess allows verifying whether a web page -or a web sitesatisfies a particular set of guidelines in order to determine its accessibility. WAI accessibility guidelines are habitually used, but EvalAccess can evaluate the compliance with any other set of guidelines if they are specified using a specifically designed XML-schema.

An environment for designing and sharing adaptation rules for accessible applications

In this work we present a design space for adaptation rules for applications accessible to people with special needs, and an environment supporting the sharing of such rules across various applications. The adaptation rules are classified according to the target user disabilities, as well as other relevant criteria useful to ease their integration in other design tools.

Tool independence for the Web Accessibility Quantitative Metric.

The Web Accessibility Quantitative Metric (WAQM) aims at accurately measuring the accessibility of web pages. One of the main features of WAQM among others is that it is evaluation tool independent for ranking and accessibility monitoring scenarios. This article proposes a method to attain evaluation tool independence for all foreseeable scenarios. After demonstrating that homepages have a more similar error profile than any other web page in a given web site, 15 homepages were measured with 10,000 different values of WAQM parameters using EvalAccess and LIFT, two automatic evaluation tools for accessibility. A similar procedure was followed with random pages and with several test files obtaining several tuples that minimise the difference between both tools. One thousand four hundred forty-nine web pages from 15 web sites were measured with these tuples and those values that minimised the difference between the tools were selected. Once the WAQM was tuned, the accessibility of 15 web sites was measured with two metrics for web sites, concluding that even if similar values can be produced, obtaining the same scores is undesirable since evaluation tools behave in a different way.

Web accessibility awareness in search engine results

The enormous amount of information available on the Internet requires the use of search engines in order to find specific information. As far as web accessibility is concerned, search engines contain two kinds of barriers: on the one hand, the interfaces for making queries and accessing results are not always accessible; on the other hand, web accessibility is not taken into account in information retrieval (IR) processes. Consequently, in addition to interface problems, accessing the items in the list of results tends to be an unsatisfactory experience for people with disabilities. Some groups of users cannot take advantage of the services provided by search engines, as the results are not useful due to their accessibility restrictions. The goal of this paper is to propose the integration of web accessibility measurement into information retrieval processes. Firstly, quantitative accessibility metrics are defined in order to accurately measure the accessibility level of web pages. Secondly, a model to integrate these metrics within IR processes is proposed. Finally, a prototype search engine which re-ranks results according to their accessibility level based on the proposed model is described.

Assessment of Semantic Taxonomies for Blind Indoor Navigation Based on a Shopping Center Use Case

Despite the growing availability of location-based services (LBS) to support pedestrian activities, we know little about the effectiveness of existing geographical web information to assist the indoor navigation of people with special needs such as the visually impaired. To characterize these indoor environments, we surveyed three different specifications about taxonomies for environmental semantic information. Survey results show that even having different scopes, the three studied specifications share considerable environmental semantic information. In order to evaluate the validity of survey results, we created a set of environmental semantic information for a shopping center, and then performed a navigation experiment with 9 visually impaired participants in the same indoor location. A smartphone-based system providing audio navigation assistance based on accurate real-time localization in the shopping center was used to complete navigational tasks. Experiment results show an overall positive assessment from participants about the usefulness of the audio messages used. We present further findings about the assessment of the different audio messages by the study participants.