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Re: Sampling

From: RichardWarren <richard.warren@userite.com>
Date: Thu, 15 Dec 2011 10:09:30 -0000
Message-ID: <3CFE789FE83B486EB8FFCD60C082CEE6@DaddyPC>
To: "Eval TF" <public-wai-evaltf@w3.org>
Eric is correct that we are evaluating (and therefore sampling) at a moment 
in time.

I presume that we will include documentation of pages visited etc. so that 
the process can be audited (we normally keep a checked list from the site 
map). This check list can be just as useful for Vivienne's monitoring.


-----Original Message----- 
From: Vivienne CONWAY
Sent: Thursday, December 15, 2011 2:11 AM
To: Velleman, Eric ; Boland Jr, Frederick E. ; RichardWarren ; Eval TF
Subject: RE: Sampling

Hi all

For my current research project, I have used a targetted sampling method. 
As well as scanning the whole site with automated tools to check for trends, 
I have chosen 5 pages from each website to check manually according to the 
WCAG 2.0 guidelines.  These pages reflect as many WCAG 2.0 checkpoints as 
possible: home page, contact us page (or something with a form), page with 
photos, page with multimedia, and a page describing their services or other 
page with some complexity.

As I check these websites repeatedly, I will check the same pages to see 
their progression (or degeneration) over time.


Vivienne L. Conway, B.IT(Hons)
PhD Candidate & Sessional Lecturer, Edith Cowan University, Perth, W.A.
Director, Web Key IT Pty Ltd.
Mob: 0415 383 673

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From: Velleman, Eric [evelleman@bartimeus.nl]
Sent: Thursday, 15 December 2011 7:22 AM
To: Boland Jr, Frederick E.; RichardWarren; Eval TF
Subject: RE: Sampling


your remark made me think of time lapse sampling:

It could be that a website/webpage changes over time on purpose. For 
example: it could show images and text related to the time of the day or the 
feeling of the owner. If the owner feels bad at 8 am, then the page is dark 
but after his first cup of coffee, the page looks bright and happy...
In that case it could be interesting to sample the same page at different 
times but I do not know how to put this into the methodology, maybe in a 


Van: Boland Jr, Frederick E. [frederick.boland@nist.gov]
Verzonden: woensdag 14 december 2011 21:48
Aan: RichardWarren; Eval TF
Onderwerp: RE: Sampling

We may also need to sample over time, since a site’s pages/content may 
change over time, which could affect WCAG2.0 conformance and/or resultant 
accessibility of the site.. or provide a date/time (required component) of 
evaluation for pages/site..  Questions that may arise in this regard are: 
how often to sample, etc. (for example,  do we just want to sample when 
there are major content changes, or do we just want to sample at regular 
intervals regardless of any perceived changes, or do we want to apply 
different strategies for different parts of a site?)

Thanks Tim Boland

From: RichardWarren [mailto:richard.warren@userite.com]
Sent: Wednesday, December 14, 2011 2:32 PM
To: Eval TF
Subject: Sampling


To reduce the effort of evaluating a large site I suggest that there are 
three methods of sampling the site’s pages/content which can be coupled with 
a barrier identification technique to avoid constant repetition.

The three sampling techniques for manual evaluation are  :-

1) Random sampling  - selecting a number of pages at random. This can be 
done by making a random selection from the site map, or to take every tenth 
(or other suitable number) of links from the site map.

2) Structure sampling – selecting the higher level structural pages such as 
Home Page, Site Map, section landing pages (usually linked from the Home 
page within the main navigation bar), any sub-section landing pages (usually 
linked to from the section landing pages, plus (if not already found) a 
sample of pages containing elements such as forms, data tables and 

3) Task orientated sampling – Completing the key tasks on the site required 
to meet the site’s purpose. This might include tasks such as to source 
certain information, place an order or participate in a discussion.

Barrier identification reduces effort further by noting examples of common 
failures in technique employed within the site and once identified and 
commented on we can ignore further occurrences within that section.

We use a combination of all three sampling methods. We start with 2 
(structured sample) to explore the site and obtain an overview of its’ 
purpose etc. Next we attempt the key tasks.  Then we do a random sample 
(skipping any pages already sampled).


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Received on Thursday, 15 December 2011 10:09:57 UTC

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