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Re: ISSUE-30 counter-proposal

From: Maciej Stachowiak <mjs@apple.com>
Date: Sun, 14 Feb 2010 08:29:29 -0800
Cc: Ian Hickson <ian@hixie.ch>, public-html@w3.org
Message-id: <46620871-2AAF-41DB-B5AB-D6FFD569EC5D@apple.com>
To: Shelley Powers <shelleypowers@burningbird.net>
Hi Shelley,

If you want to argue against the studies Ian cited, please do so by  
using facts to refute them, instead of just casting vague aspersions  
on Ian's integrity. Examples of fact-based arguments would be: (1)  
cite specific methodological flaws; (2) perform or cite a better study  
that finds different results. That's what a scientist peer reviewing a  
study would do, they don't just accuse each other "bias".


P.S. Of the four studies cited below, only one was performed by Ian  
and at least two include the full raw data on which they base their  
conclusions. Some of the studies are also endorsed by noted Web  
accessibility experts. A useful thing to do would be to follow the  
links, read over the studies, and report back to the Working Group on  
the specific problems you find with any of these studies.

On Feb 14, 2010, at 7:37 AM, Shelley Powers wrote:

> Ian Hickson wrote:
>> Here's a counter-proposal for ISSUE-30:
>> == Summary ==
>> The longdesc="" attribute does not improve accessibility in  
>> practice and should not be included in the language.
>> == Rationale ==
>> Several studies have been performed. They have shown that:
>> * The longdesc="" attribute is extremely rarely used (on the order  
>> of 0.1% in one study). [http://blog.whatwg.org/the-longdesc-lottery]
>> * When used, longdesc="" is extremely rarely used correctly (over  
>> 99% were incorrect in a study that only caught the most obvious  
>> errors [http://blog.whatwg.org/the-longdesc-lottery]; the correct  
>> values were below the threshold of statistical significance on  
>> another study that examined each longdesc="" by hand [http://wiki.whatwg.org/wiki/Longdesc_usage] 
>> ).
>> * Most users (more than 90%) don't want the interaction model that  
>> longdesc="" implies. [http://webaim.org/projects/screenreadersurvey2/#images 
>> ]
>> * Users that try to use longdesc="" find it doesn't work ("Who uses  
>> this kind of thing? In my experience [...] it just didn't work.  
>> There was no description.") [http://www.cfit.ie/html5_video/Longdesc_IDC.wmv 
>> ].
> I'll let the accessibility folks respond to the accessibility  
> components of your proposal, but we've had discussions in the past  
> about your "studies", and the flaws associated with them.
> First of all, you've not provided access to the same data, so your  
> results cannot be confirmed or denied.
> Secondly, you have a bias in the results, and bias has been shown to  
> compromise the integrity of studies. That's why researchers use  
> blind studies, in order to ensure their biases and assumptions do  
> not impact on the results.
> Third, there is no way to determine the cause of results found on  
> the web. Were incorrect uses because longdesc is inherently too  
> difficult for users? Or because it was inadequately documented? What  
> is the age of the results, and is there a trend to a more positive  
> useful effect, as understanding grows about longdesc?
> There is no way to form an irrefutable conclusion from nothing more  
> than scraped data found on the web -- there are no controls in place  
> to separate out the various cause agents, and focus specifically on  
> one or another. The most you can do is make an anecdotal  
> observation, and again,  your own biases in regard to longdesc  
> undermine the effectiveness of the observation.
> You don't have to take my word for any of this: I would suggest you  
> run my comments by your Google "experts", and I think you'll find  
> that they agree with me.
> Therefore, your studies cannot, by themselves, be used to form a  
> legitimate decision about longdesc, or any other aspect of the HTML5  
> specification. All that remains is your other arguments, which I'll  
> leave to others to debate, or not.
Received on Sunday, 14 February 2010 16:30:04 UTC

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