- From: Gregg Vanderheiden <gv@trace.wisc.edu>
- Date: Mon, 10 May 2004 09:56:56 -0500
- To: <w3c-wai-gl@w3.org>
- Message-ID: <auto-000031960302@spamarrest.com>
Sorry I don't know where the implication that the times needed to be in round numbers or that the numbers weren't derived from user testing came from - but that was not my intention. I was talking about results from user testing. Also - this was not meant to be a 'final determination' but rather a sniff test. If something slows people with disabilities down the same proportionate amount as people without disabilities - then I look at it more carefully to see if it is indeed just a usability problem rather than an accessibility problem. Here I am defining accessibility problems as problems that result from a person having a disability and that affect them in ways or in proportions that are not experienced by everyone else (without that disability). Again - please note that this is NOT something that I am proposing as a definition or for use by our group. It was simply something I found useful when looking at problems in this area - and I posted to the list because others found it an interesting idea to roll around in their heads. ciao Gregg -- ------------------------------ Gregg C Vanderheiden Ph.D. Professor - Ind. Engr. & BioMed Engr. Director - Trace R & D Center University of Wisconsin-Madison _____ From: w3c-wai-gl-request@w3.org [mailto:w3c-wai-gl-request@w3.org] On Behalf Of Gordon Montgomery Sent: Monday, May 10, 2004 7:17 AM To: w3c-wai-gl@w3.org Subject: Re: General Usability DetecVS tor Time cannot be used as a reliable indicator of usability. Firstly you will not get "times" that are nicely differentiated like 2mins vs 4mins It will be more like 2.1 mins vs 2.25 mins. Then there's the issues of when the task started, the level of verbosity of the participant and level of success related to the completion of the task. Finally, satisfaction plays a big part too. Just because a task takes a few extra seconds may not mean that participants are any less satisfied with the effectiveness [their success] or efficiency [their effort] of the interface. In fact those few extra seconds may indeed add to satisfaction in some cases and leave the participant feeling that the interface is more usable. So to answer your question you cannot differentiate [nor should you] accessibility and usability issues a priori. The only way to know if issues are particular to the disabled is to test with those intended users. That involves running a formal usability test. Accessibility has a lot to do with the coding we use for web pages etc and that sadly is where it has always lost traction with the wider commercial world. Until we make testing with real users the central theme then accessibility will continue to reside in an esoteric, "not my problem" backwater as far as most corporations are concerned. Thanks, Gordon. --------------------------------------------------------------------- "Are you still wasting your time with spam?... There is a solution!" Protected by GIANT Company's Spam Inspector The most powerful anti-spam software available. http://mail.spaminspector.com ----- Original Message ----- From: Gregg Vanderheiden <mailto:gv@trace.wisc.edu> To: w3c-wai-gl@w3.org Sent: Monday, May 10, 2004 12:46 AM Subject: General Usability DetecVS tor In discussions on our last call "usability" came up since it was a question from one of our reviewers How do we separate "Accessibility / Usability problems that are specific to disabilities" From "usability issues that are faced by all users" One test I have sometimes found useful in examining this question is "Does it multiply the time and effort for people with disabilities by the same amount as people without disabilities?" If the multiplier is the same - then it may be a general usability issue. For example Good page 2 min for no disability Good page 4 min for screen reader user Bad page 3 min for no disability Bad page 6 min for screen reader user This bad page appears to be 50% harder for both groups. This looks more like a general usability problem rather than accessibility since it slows everyone down by the same factor Another example Good page 2 min for no disability Good page 4 min with screen reader Page 2 - 3 min for no disability Page 2 - 10 min with screen reader. Page 3 - 3 min for no disability Page 3 - cannot get at some of the information with screen reader. These look like accessibility problems Page 2 is much more than proportionately harder (250% vs 50%) Page 3 is inaccessible Just passing along in case it is of use to others in thinking about the problem Gregg ------------------------ Gregg C Vanderheiden Ph.D. Professor - Depts of Ind. Engr. & BioMed Engr. Director - Trace R & D Center University of Wisconsin-Madison < <http://trace.wisc.edu/> http://trace.wisc.edu/> FAX 608/262-8848 For a list of our list discussions http://trace.wisc.edu/lists/ <http://trace.wisc.edu:8080/mailman/listinfo/>
Received on Monday, 10 May 2004 11:02:11 UTC