Comments on: The Difference between Web Site Usability and Accessibility

By: Whitney

Whitney — Sat, 23 Jul 2011 15:20:18 +0000

Karl, I think you are missing the point about usability and accessibility. Of course, it makes little sense to start ensuring that a site is accessible through usability testing. It also makes no sense to spend time usability testing a site with obvious problems that need to be fixed.

But, one the technical access issues are dealt with, you still might have a site that is accessible, but not usable. And that’s where usability testing comes in. It’s especially important for design teams that do not have much experience with how people with disabilities use the web.

I think it’s a maturity question. Are you getting from “unacceptable to tolerable” or from “good to great.” I’d argue that you don’t get to great without a deep understanding of all of your users.

By: Justin Mifsud

Justin Mifsud — Mon, 18 Jul 2011 18:02:03 +0000

Karl, Doug, thanks for the interesting debate. In my personal opinion, I think that accessibility is more structured, defined and well documented when compared to usability. In fact, adhering to WCAG, Section 508 (US), the Stanca Act (Italy) and other country-specific accessibility guidelines is a must when developing government sites. On the contrary, as I said above, there are several usability guidelines that have been developed – some even before the advent of the WWW. Most times it is difficult to choose between them as they are abstract and conflicting. Indeed, a study by Jakob Nielsen had showed that different experts came out with different interpretations when they evaluated the same set of web sites for usability. Long story short, adhering to WCAG, Section 508 etc is easier than trying to make a web site usable. Also, due to the specific guidelines for accessibility, it is easier to build an automated accessibility evaluation tool (there are lots of those available) but it is harder to build such a tool for usability. There is also a shortage of usability experts and their services are quite expensive.

By: Justin Mifsud

Justin Mifsud — Mon, 18 Jul 2011 17:51:00 +0000

Actually, Web Axe, making a web site backward compatible with older (yet recent) technologies is also a usability practice and not only reserved for accessibility. Thus, for example, loading an image when Flash is not available on the user’s browser so that the UI is not broken is a usability practice too. What I disagree with you is supporting old technology such as IE6 since it is likely that you may end up adding several images and JS files so as to compensate for the lack of support of CSS. Whilst this may not seem to be related to usability, it is indeed if the addition of this extra code and resources slows down the web site.

By: Emma

Emma — Wed, 13 Jul 2011 10:52:17 +0000

When I’m working with students, I tend to get them to think about usability being related to the ease of use of a site generally, & accessibility being related to whether or not someone with a disability has greater difficulty using the site.

We also tend to get them to think about e.g people with dyslexia – (also useful for non-native readers), as well as those things are easier to test automatically.

By: Karl Groves

Karl Groves — Mon, 11 Jul 2011 22:34:10 +0000

Doug, I would be willing to bet that if you’ve conducted actual usability studies with persons who are blind, the highest impact problems you found in testing were the kinds of things which were primarily technical in nature. I find that usability testing is an inefficient and expensive method of finding accessibility data. This is because for the most part the issues can be found more quickly discovered using automated testing and expert review. If used at all, user testing for accessibility data should be reserved for instances where all of the issues uncovered through automated and expert review have been resolved. After all, why spend time and money (persona development, recruitment fees, labs, stipends, etc.) finding data you can find more efficiently? In over 8 years doing accessibility and usability, I’ve yet to see an instance where user testing yielded results not discovered during a review by a skilled accessibility expert.

By: Doug McKay

Doug McKay — Mon, 11 Jul 2011 13:31:46 +0000

I completely agree and just because something is check marked as accessible doesn’t mean that is a good experience for users. Karl in my experience with at least blind users there is more than technical issues that can be discovered through usability testing. The flow of things like page read order and the addition of subtle and non-subtle context cues that really makes the experience better.

By: Web Axe

Web Axe — Fri, 08 Jul 2011 15:33:10 +0000

Thanks for the concise and factual article. I agree with this point: in addition to providing for people with disabilities, I feel web accessibility also includes those using low-end technology (lowband, IE6) and also when technology is unavailable (JS firewall, broken mouse, no audio).

By: Karl Groves

Karl Groves — Fri, 08 Jul 2011 13:09:24 +0000

Justin,

At this risk of being too blunt, I would truly love to dislodge usability folk from the belief that usability and accessibility are the same thing. While there may be some similarities, equivocating usability and accessibility is a huge mistake.

ISO defines usability as “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”. From that definition, one could assume that accessibility would merely be an extension of usability in that it focuses on users with disabilities. What’s missing, however, is the approach.

Hardcore usability experts and leaders in the field are typically people with cognitive psychology and ergonomics backgrounds. While you can certainly use typical usability testing methods such as cognitive walkthroughs to measure effectiveness, efficiency, and satisfaction to gather accessibility data, the issues uncovered during such testing with users with disabilities are more likely than not going to be purely technical in nature than what you’d find during testing of the same system with users who are not disabled.

I typically find this type of equivocation to be caused by the fact that usability people simply don’t understand accessibility. According to the WAI (http://www.w3.org/WAI/bcase/fin.html#increase-use) only 13 of the 61 WCAG 2.0 Success Criterion are claimed to have a benefit for usability. Of those 13, only 3 of them are Level A Success Criteria. There are 9 more Level A Success Criteria unmapped to Usability. Clearly usability and accessibility are not the same and we should stop equivocating them.

By: Whitney Quesenbery

Whitney Quesenbery — Fri, 08 Jul 2011 12:20:29 +0000

Yes. Usability and accessibility are part of the same spectrum, defining whether a product (or site) can be used by us human. By the way, the updated ISO standards do two important things. First, they bring all of the usability, accessibility and design process standards into one “family” (the 9241 series for standards geeks). Second, they define accessibility as usability for a broader range of human abilities.