Importance of Usability and Accessibility for Web Design

The relationship between accessibility and usability can be a contentious issue especially with the advent of new web technologies. Does accessibility have an adverse effect on usability and vice versa and is this in any way affected by new web technologies? With the advent of new web technologies, it is thought by some that the two supposedly bipolar methodologies of web design and evaluation contradict one another even more. In order to determine if this is, in fact, true this paper will look at the effect of new web technologies on accessibility and usability and the current practices in each of these areas. This paper considers various views on this topic, compares definitions and methodologies and concludes that even when using new web technologies, embracing both sets of practices and recognizing their points of similarity, it is still possible, with considered and judicious use of new web technologies to make a web design that is both usable and accessible.

Some accessibility practitioners believe that by applying new web technologies to a web design, that because of the added level of complexity, they create another barrier to disabled people (Everett 2006).

Some usability practitioners believe that by enforcing accessibility practices that the interactivity will in some way suffer (Koch 2002). In terms of new web technologies is this still the case.

Is there any merit in these beliefs? Can common ground be found to achieve some kind of balance?

There appears to be a lack of clarity of what constitutes a usable website and a misunderstanding of what constitutes a truly accessible website.
The aim of this paper is to discuss the relationship between usability and accessibility by firstly looking at the differences between them and where they overlap. We will then need to understand current thinking on the relationship between accessibility and usability and how it is affected by current web technologies. Will Web Standards and new web technologies have an effect on accessibility and usability? With the advent of Web standards (Featherstone et al. The Web Standards Project 1998) and updated web accessibility guidelines (Henry et al. W3C 2008), it has become easier for developers to create sites that are more usable and accessible. This paper will also investigate technologies such as AJAX (Asynchronous JavaScript and XML)(Garrett 2005), and whether this will have any further effect on the relationship between accessibility and usability

1) Usability

The generally accepted definition for usability in ISO 9241 states: "the extent to which a product can be used by specified users to achieve specified goals with effectiveness, efficiency, and satisfaction in a specified context of use"

Usability is defined by five quality components (Nielsen 2003):

Learnability: Ease with which a basic task can be completed on the first attempt. Efficiency: The speed with which a task is performed Memorability: The ease with which an interface will be remembered. Errors: The number and severity of errors Satisfaction: The level of enjoyment or pleasure when using an interface

An extension of usability is the term User-Centered Design (UCD) (Preece et al. 2006), where users are involved throughout the lifecycle of website developments by using structured methodologies in order to determine and meet all the needs of the target user (Usability.gov 2009).

Some of the techniques used include (Usability.gov 2009):

Usability testing - Representative users are observed while attempting to complete set tasks. Notes on the observations of user behavior and comments are made. Card sorting - Participants arrange and even label cards representing site content into logical groups and categories to inform the information architecture of a site design. Individual interviews - Individual participants are interviewed typically for 30 minutes to an hour either in person, by telephone, or by any means available which allows conversation. These interviews can be formal or informal and do not involve observation. Contextual interview or field studies - Contextual interviews are similar to user testing because the users are observed, however, they are not given a set of the task but are rather observed in there natural environment. Observers also take notes. Surveys - These are used to obtain data from large groups of people in a relatively short time and are normally used to gather user requirements. They can also be used for summative usability evaluation. Focus groups - These are usually a discussion among eight to twelve current users or potential users or stakeholders of your site conducted by an experienced moderator. Focus groups typically last approximately two hours and cover a range of topics that are decided on beforehand. Task analysis - Is used to determine the typical tasks that users perform to achieve a particular goal. Work patterns are studied and broken down to provide a list of tasks and the order in which they are performed. Prototypes - Are representations of your website/application shown to users in order to inform the design and determine any major defects before proceeding with further development. These can range from paper drawings (low-fidelity) to near complete products (high-fidelity). Expert evaluations - Experts are asked to evaluate sites for usability employing various methods such as heuristic evaluation where sites are evaluated against a set of usability principles. Other methods such as Cognitive walkthroughs and pluralistic evaluation are used (Preece et al. 2006).

Will usability practices need to include accessibility practices in order to include people with disabilities or will do this to minimize the usability of web products?

2) Accessibility

The web gives people with disabilities the ability to do things that they would be unable to do via any other avenue. The web offers them freedom and independence. However, all of these possibilities are removed if a website is not created in an accessible way.

Essentially accessibility can be defined as access for everyone no matter what disability they suffer from (Berners-Lee, via Henry W3C 2009).

Other have a more flexible approach such as Clark (2002) where he suggests that allowances for disabled users should be made to make a website accessible.
Another term used in connection with Accessibility is Universal Design, which incorporates elements of usability with the goal of making websites or any product as usable as possible by as many people as possible without requiring adapted or specialized design. (Mace 2008)

The guidelines by which most accessibility practitioners develop and evaluate websites is Web Content Accessibility Guidelines (WCAG) 2.0 which are updated standards developed by The World Wide Web Consortium (W3C). These are written to accommodate new technologies and provide better and more comprehensive help for developers and designers when trying to make websites accessible. These standards consist of 12 guidelines that are organized under 4 principles: perceivable, operable, understandable, and robust. For each guideline, there are testable success criteria, which are at three levels of priority: A, AA, and AAA with all A guidelines having the highest priority (Caldwell et al. W3C 2008).

The four principles of the WCAG 2.0 guidelines can be explained as follows (Caldwell et al. W3C 2008):

Perceivable - Web content should be made available to any or all of the senses - sight, hearing, and/or touch Operable - Interface objects such as forms, controls, and navigation must be operable independent of the input method Understandable - The site's content, information, and interface must be understandable to the target audience Robust - Sites can be used reliably by a wide variety of user agents such as web browsers, mobile devices, and assistive technologies

The W3C also lists various methods for evaluating websites for accessibility to determine their compliance with WCAG (Abou-Zahra et al. W3C WAI 2008). Various methods including preliminary reviews, manual and automated evaluation tools, are used to determine compliance.

When developing websites whether with new technologies or not it is recommended that Web Standards coding practices should be used to attain conformance with WCAG 2.0.

Web standards are technologies and practices established by the World Wide Web Consortium (W3C), along with other groups and standards bodies for creating and interpreting web-based content. By making use of these technologies it is possible to create web content that benefits a greater number of users and at the same time making this content usable in the long-term regardless of technology changes (Featherstone et al. WASP 2006).

The Web Accessibility Initiative (WAI) of the World Wide Web Consortium (W3C) has developed an Accessible Rich Internet Applications Suite (ARIA) in order to make rich internet content more accessible for people with disabilities (Henry et al. W3C 2009).

This suite is currently not fully supported in all user agents (browsers) and AJAX libraries (Henry et al. W3C 2009).

Will updated accessibility practices be able to enhance or be incorporated into usability practices?

3) Conclusion

To make sites that are usable and accessible we will need to change our thinking of usability. Is your site still usable if sighted people can fully and conveniently use it but it is a frustrating exercise for a blind person? (Clark 2003)

In understanding the concept of an accessible site we have to understand what an accessible site is. A disabled person's experience of a website does not have to be identical to that of an able-bodied person. If accessibility features are simple and well written, they should be unnoticed (Clark 2002). Clark (2002) reiterates, "Equality is a misnomer. Equivalency is the goal."

As can be seen from the above discussion there is an overlap between the definitions and methodologies employed by accessibility and usability practitioners and that there is scope for accessibility guidelines to be employed by usability practitioners and vice versa. However, this is not simply a case of making a universal set of guidelines, as firstly accessibility and usability issues cannot be universally grouped and that there are distinct groups of accessibility issues. Secondly, the use solely of guidelines is fraught with controversy and do not necessarily guarantee that a site will be accessible or usable.

Involving users both disabled and able-bodied throughout the project lifecycle is the most effective approach in achieving the most usable and accessible product. Involving disabled users is also makes good business sense.

Web 2.0 technologies do have an effect on the relationship between accessibility and usability. For them to not have a negative effect they need to be used with discretion always bearing in mind that they add a level of complexity for both able-bodied and disabled users.

Therefore we can conclude that by embracing the techniques and methodologies and recognizing points of similarity between usability and accessibility practices, and with modest and careful, considered use of new web technologies a web design can be made both usable and accessible.

Accessibility practitioners and researchers can incorporate usability techniques to improve 'usable accessibility'. User experience designers and researchers can incorporate accessibility to make their designs work better for more people in more situations. Addressing accessibility, usability, and inclusion together can more effectively lead to a more accessible, usable, and inclusive web for everyone.