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RE: 100% conformance for the pages sampled...

From: Velleman, Eric <evelleman@bartimeus.nl>
Date: Thu, 19 Jan 2012 21:49:24 +0000
To: Alistair Garrison <alistair.j.garrison@gmail.com>, Eval TF<public-wai-evaltf@w3.org>
Message-ID: <3D063CE533923349B1B52F26312B0A467565CC@s107ma.bart.local>
Hi Alistair,

Yes, I think that was also my impression of the Telco. 100% conformance on the sampled pages. This means no margin for error.

In the Netherlands this 100% conformance requirement was not accepted by stakeholders. The Dutch normative document says:

Source: www.drempelvrij.nl

In assessing the conformance of a given website to the Web Guidelines, it is unavoidable to allow a margin of error.  While maintaining and encouraging the pursuit of the 100% score in order to ensure the quality and accessibility of websites, this margin of error combines full conformance with a realistic tolerance of human error. This will also serve to promote the acceptance of the Web Guidelines within the web development community. While full conformance is the goal, the margin of error allows an otherwise accessible website to claim conformance, even with a very small number of human errors.

The obvious way to allow for a margin of error would be to indicate a percentage range per success criterion. Websites falling within this range could still claim conformance. The problem with this method is that the relative importance of each guideline must be calculated, and this relative importance could become a point of discussion.

A better method for allowing for a margin of error is to make a distinction between incidental and structural errors:

An incidental error is one which occurs infrequently; Apart from that, the given guideline has been correctly implemented throughout the website.

A structural error is one which, in most cases, occurs more frequently; the same type of error is made repeatedly. Structural errors will also often indicate larger problems within the technical systems or processes behind the website which can be detrimental to quality and accessibility. 

Please note: 
	In situations where there are very few instances of a given element (such as a website containing only two tables), an incidental error is considered structural because of the relative impact it may have on the site as a whole. 
	Errors in navigational elements and (parts of) key scenarios are considered as structural errors.
	Incidental errors cannot exceed 10 % of the instances of each element within the sample. 

Although the incidental/structural error distinction method is not entirely based on fixed numbers or percentages, the different types of error are easily to distinguish. This makes the resulting evaluation realistic and measurable and will more accurately pinpoint problem areas.

For an inspection, the complete checklist must be completed for the level that is required. In order to claim conformance to the Web Guidelines, a site must score as either fully conformant (conformant without errors) or must show only incidental errors per checkpoint. Any structural errors will indicate non-conformance to a given checkpoint. All found errors are to be recorded, whether incidental or structural, in an effort to encourage improvement and full conformance.

Kindest regards,


Van: Alistair Garrison [alistair.j.garrison@gmail.com]
Verzonden: donderdag 19 januari 2012 22:02
Aan: Eval TF
Onderwerp: 100% conformance for the pages sampled...

Dear All,

If I understood correctly from this afternoon's EVAL TF telecon - there was a suggestion that we should (at a minimum) require the representative sample pages to be in 100% conformance with WCAG 2.0 (at the chosen level) in order to say the site conforms (at that level).  If this was the case, I strongly agree with it (meant to write it in the IRC at the time).

In addition, I noted from some a worry about telling a website owner (a client, etc) that their website doesn't conform - especially when they might have tried hard to do so.  To my mind, worries of this kind should not deter us from asking for nothing less than 100% conformance (on any given sample).  The person that does the MOT on my car has absolutely no worries about telling me about any failures, but possibly that's because everyone doing MOTs requires 100% conformance from a car for a pass.

Surely, we want people to try their absolute best to conform 100%.  We must encourage them to shoot for the stars (100% conformance) - some, of course, will initially only hit the moon, but they will at least know what is expected from them... Let's not, however, start to congratulate people for simply getting off the ground - that time must have passed long, long, long ago.

Anyway, look forward to seeing you all on the list.

Received on Thursday, 19 January 2012 21:53:57 UTC

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