Success criteria for accessability testing

[Benjamin Davies]

Hello. I am about to begin designing a usability study on a government
website and evaluating the accessability of the site will be a big
component. I'm looking for advice on comparing data from the
visually disabled participants (using screen readers and magnifieers)
to participants with typical vision.

1. Is there an expected relationship between typical participants and
the visually disabled (ie, is it possible to say that "if the
disabled participants have time-on-task within 35% of non-disabled
participants the task is considered to not have accessability
problems"?) If so, what should be the percentage difference?

2. Should I create test tasks as I would normally and then adapt them
as necessary for the disabled or should I have some or all of the
tasks specifically designed for the disabled?

3. Are there any common problems with installation and settings with
JAWS, Dragon Reader, and Zoomtext (the software we'll be using) I
have limited experience with them and while I plan to working with
them. I plan to spend a lot time with them in preparation for the
test but making sure I have the test environment propperly setup is a
worry that I'd like to remove.
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[Nick Dunn-2]

>From my experience #3 might be your biggest sticking point.
Screen-reader users will know keyboard shortcuts for the common tasks
of navigating through a page, and these vary from application to
application. I do wonder whether a user would struggle if presented
with an unfamiliar assistive client.


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Posted from the new ixda.org
http://www.ixda.org/discuss?post=47098


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[William Hudson]

Benjamin -

Some comments below. I hope these help.

Regards,

William Hudson
Syntagm Ltd
Design for Usability
UK 01235-522859
World [phone]
US Toll Free 1-866-SYNTAGM
mailto:william.hudson@...
http://www.syntagm.co.uk
skype:williamhudsonskype

Syntagm is a limited company registered in England and Wales (1985).
Registered number: 1895345. Registered office: 10 Oxford Road, Abingdon
OX14 2DS.

> -----Original Message-----
> From: discuss-bounces@... [mailto:discuss-
> bounces@...] On Behalf Of Benjamin Davies
> Sent: 28 October 2009 9:37 AM
> To: discuss@...
> Subject: [IxDA Discuss] Success criteria for accessability testing
>
> Hello. I am about to begin designing a usability study on a government
> website and evaluating the accessability of the site will be a big
> component. I'm looking for advice on comparing data from the
> visually disabled participants (using screen readers and magnifieers)
> to participants with typical vision.
>
> 1. Is there an expected relationship between typical participants and
> the visually disabled (ie, is it possible to say that "if the
> disabled participants have time-on-task within 35% of non-disabled
> participants the task is considered to not have accessability
> problems"?) If so, what should be the percentage difference?

No. Because of the massive difference between the 'parallel processing'
that we take for granted when visually scanning a page and the
serialization that is performed by screen readers, there is almost no
correlation at all. Users with typical vision might find something
trivially quick to do while disabled users may find it impossible.

> 2. Should I create test tasks as I would normally and then adapt them
> as necessary for the disabled or should I have some or all of the
> tasks specifically designed for the disabled?

I would suggest that the tasks should be based on common scenarios (user
stories, use cases or whatever) for that site. If it's an important
task, everyone should be able to do it. There *may* be some tasks
specific to disabled users, but I would suspect these to be in the
minority.

> 3. Are there any common problems with installation and settings with
> JAWS, Dragon Reader, and Zoomtext (the software we'll be using) I
> have limited experience with them and while I plan to working with
> them. I plan to spend a lot time with them in preparation for the
> test but making sure I have the test environment propperly setup is a
> worry that I'd like to remove.

JAWS is pretty straightforward but advanced users may want to do some
customization. I am not familiar with Dragon Reader. Do you mean Dragon
Naturally Speaking? If so, the system needs some training for each user.
Allow around 15-20 minutes for this and make sure you have a good
quality headset microphone. (There are other solutions but a headset
microphone is the most reliable for many purposes.) I don't know about
Zoomtext.
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