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Another Efficacy Example

From: Wayne Dick <wayneedick@gmail.com>
Date: Thu, 4 Oct 2012 01:55:26 -0700
Message-ID: <CAJeQ8SDRd0XzjNNhRR6J5DUGH9Q_SdTVi6j5qerbLqmZ4349+Q@mail.gmail.com>
To: public-wai-rd-comments@w3.org
Dear Metrics Group,

More on efficacy

Consider the example of SC 2.4.3
2.4.3 Focus Order: If a Web page can be navigated sequentially and the
navigation sequences affect meaning or operation, focusable components
receive focus in an order that preserves meaning and operability.
(Level A)

Consider the following experiment:
1.  State the treatment goal of this criterion.
2. Determine some measures of efficacy.  Say the average number of
actions required to accomplish a task with keyboard decided by the
average number of actions needed to do the same task with a mouse.  A
ratio.
3. Determine sample sizes for keyboard users, mouse users and web
pages that meet 2.4.3, so that we can get statistically significant
results.
4. Run the experiment and determine if 2.4.3 does produce something
close to equally effective access.
5.  Of course we would have to determine equally effective.  For
example if the task was essential for employment, could a person get
the same amount of work done with this keyboard access?

I hope this helps to clarify my concept of efficacy vs. validity.

Sincerely,
Wayne Dick
Received on Thursday, 4 October 2012 08:55:54 GMT

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