Accessible Electronic Content: Guidelines

Evaluating Accessibility

There are some excellent tools available to aid in the task of evaluating your Web pages for accessibility. While no software can do the whole job, automated checkers can flag both obvious errors and areas of potential concern, where human judgment is key. Best of all, many of these accessibility tools are free! If you have questions about these tools or evaluative process, contact ITS Web Services. For more information on format converters and other related tools, see the Tools & Services page. A handout version PDF of this page is available.

When Should I Evaluate? | Evaluation Tools | Emulating the User Experience | Human Judgment | Conclusions

When Should I Evaluate Accessibility?

During development: As you build, using accessibility tools will help 'keep you honest' and designing according to standards. Intelligent design from the start will save you - and your users - worlds of pain later on.

Before going live: A formal accessibility evaluation can both catch last-minute problems and provide some validation for your hard work during the development process.

Periodically on existing sites: Not just for retrofitting - most of the accessibility problems an automated checker will find are easily correctible. By far the most common error is a missing ALT attribute in an image tag. Fix them on the fly!

When Should I Evaluate? | Evaluation Tools | Emulating the User Experience | Human Judgment | Conclusions

Dirt Cheap Tools for Accessibility Evaluation

A continual awareness of accessibility concerns should be a part of the development process, and these tools allow you to perform both informal spot checks and more thorough analysis as you build. Evaluation tools fall into three main general categories: Web-based, desktop applications, and toolbars. All have their place in an integrated development environment. In addition to evaluation, there are also easy ways to emulate the experience of a user with disabilities, which can be very informative (see Emulating the user experience). All of the tools mentioned here are either free or donation-ware.

Toolbars

Accessibility toolbars are a great resource. They make the developer's job easier by aggregating disparate utilities in one convenient location. The fact that they are browser-specific is the only real downside to toolbars, but happily there are good ones for IE and Mozilla.

The Vision Australia Web Accessibility Toolbars, for Internet Explorer, has a solid focus on accessibility, and provides an astonishing array of features, from browser window re-sizing to links to popular Web evaluators.

Chris Pederick's Firefox Web Developer Extension Toolbar offers many of the same gee-whiz emulation tricks for Mozilla/Firefox users, as well as a host of general Web development tools you really can't live without.

Mozilla users should keep their eyes on WAIZilla, which is not yet ready for prime time but promises great things.

Browser Extensions

Two useful Firefox extensions are in active development that are great evaluative tools for Web developers. Although these are great tools, remember that assistive technology users at Carolina will typically be using Internet Explorer - do your testing in that browser as well.

Fangs is a Firefox extension that provides a textual representation of the content of a Web page, much like delorie.com's lynx viewer. In a way it is a stronger tool, because the output is strictly linearized, without structural features like line breaks. It is a work in progress, but pretty useful in the current beta form. Fangs' Sourceforge project page is also a good source of information on this extension.

Speak It is a Firefox extension that provides text-to-speech functionality using the Microsoft Win32 Speech API. This is not a full-fledged screen reader, but if you want to hear how a page will generally render aurally, it's simple and useful. Speak It is a re-write of FoxyVoice.

Web-Based

If you don't want to add a toolbar that provides direct links, you can always bookmark the evaluation and emulation tools you choose to use.

First ports of call for any self-respecting developer are the W3C's markup validator and CSS validator - if your code validates, chances are it is well on the way to effective accessibility.

Web accessibility checkers examine your code and generate a report based on parameters you set - which standard (508, WCAG, etc) and the amount of verbosity you require. Watchfire WebXACT is an excellent product, and the WebAIM initiative's WAVE is also good. These render output differently, and usability isn't always that great. Try these (and others!) and go with the one that you find easiest to interpret.

Desktop

There are software applications that operate outside the browser - these are frequently more robust than their Web-based counterparts, but have their own limitations - platform specificity being chief among them.

IBM's aDesigner provides a thoughtful interface and genuinely useful output in a desktop application. The A-Prompt accessibility tool, from the University of Toronto, is feature-rich but perhaps a little more complex to use.

When Should I Evaluate? | Evaluation Tools | Emulating the User Experience | Human Judgment | Conclusions

Emulating the User Experience

While automated testing tools can compare your pages to a set of guidelines and give you a thumbs up or thumbs down, there are other resources that can help you experience the page as a user might. This is often much more informative from a design standpoint. The best emulator, of course, is no emulator at all, but a real user instead. If you know a person with a disability who would be willing to give you feedback, by all means take advantage of the opportunity.

Using assistive technology can also be useful, since users with disabilities will be using it as well. The learning curve is often steep, however, and screen readers vary in price from $150 (IBM Home Page Reader) to $1000+ (the JAWS screen reader, UNC's campus standard). Recent builds of the Opera browser include basic text-to-speech functionality, and Firefox extension Speak It, mentioned above, is also a useful free tool.

To visualize the browsing experience from the point of view of a blind or low-vision user, try linearizing your site by using a non-graphical browser, like LYNX. Delorie.com kindly hosts a LYNX emulator if you don't have access to a command line, and the Firefox extension Fangs is also very handy.

When Should I Evaluate? | Evaluation Tools | Emulating the User Experience | Human Judgment | Conclusions

Human Judgment: No Machine Can Do It All

Like most things worth doing, accessible design is fraught with judgment calls. Some accessibility guidelines simply can't be checked off by an automated tool. Consider screen contrast - it is a subjective value, and you need to actually see it to decide if it is acceptable or not (Juicy Studios may not agree; see their nifty Contrast tool). In other cases, it is actual content that needs human judgment - the description in alternate text, for example. The bottom line is that you cannot rely exclusively on the wonderful tools described in this document. The W3C Web Accessibility Initiative has lots of resources related to evaluation, and handy guidelines you can follow in your role as the human half of the testing team.

When Should I Evaluate? | Evaluation Tools | Emulating the User Experience | Human Judgment | Conclusions

Conclusions

The proper tools, used consistently throughout the development process, will ease the accessibility burden dramatically. Taking the time to install - and use - a browser toolbar will make informal spot checks very straightforward, and Web-based or desktop applications can provide the features you need for a more comprehensive evaluation.