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RE: Sampling

From: Velleman, Eric <evelleman@bartimeus.nl>
Date: Wed, 14 Dec 2011 22:22:06 +0000
To: "Boland Jr, Frederick E." <frederick.boland@nist.gov>, RichardWarren<richard.warren@userite.com>, Eval TF <public-wai-evaltf@w3.org>
Message-ID: <3D063CE533923349B1B52F26312B0A467323A1@s107ma.bart.local>

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 footnote?


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 multi-media.

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).

Received on Wednesday, 14 December 2011 22:23:10 UTC

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