RE: Priorities - a proposal

I think we are going for the same meaning but this terminology might
help...

P1: MUST. 		Would prevent users from gaining access to this
feature, information, or control if this was not done.
P2: Like. 		Would significantly improve usability if this
was done.
P3: Nice to have.	Would improve usability if this was done, but is
not required for basic use.

 -----Original Message-----
From: 	Gregg Vanderheiden [mailto:gv@trace.wisc.edu] 
Sent:	Sunday, March 18, 2001 2:08 PM
To:	'Charles McCathieNevile'; 'WAI Cross-group list'
Subject:	RE: Priorities - a proposal

Hmmmm

We can look at this but I think P1 might stay at "impossible".   I like
the
10x but that starts to get subjective, and 10x for how many people?
One?
Most?

Ditto for P2 and P3.

P2 I think is SERIOUS usability problems.      Maybe here we can use a
multiplier. (with and without) to divide 2 and 3.


-- ------------------------------
Gregg C Vanderheiden Ph.D.
Professor - Human Factors
Depts of Ind. and Biomed. Engr. - U of Wis.
Director - Trace R & D Center
Gv@trace.wisc.edu, http://trace.wisc.edu/
FAX 608/262-8848
For a list of our listserves send "lists" to listproc@trace.wisc.edu


 -----Original Message-----
From: 	wai-xtech-request@w3.org [mailto:wai-xtech-request@w3.org]  On
Behalf
Of Charles McCathieNevile
Sent:	Sunday, March 11, 2001 10:34 AM
To:	WAI Cross-group list
Subject:	Priorities - a proposal

We have what we claim is a simple rule for distinguishing between P1 and
P2
items - whether they make things impossible. The difference between P2
and
P3
seems much less well defined.

I don't think there will ever be a hard and fast rule, but a bit better
guidance would be good. In addition to the definitions that we use at
the
moment, (essential, important, helpful, or some variation) I suggest we
look
at efficiency as a rough guide. For example, something that takes 10
times
as
long or more, and is a task that "normally" takes several minutes
suddenyl
becomes a task that takes an hour or more. In this case I would suggest
that
it represents a barrier of P1 level - in particular in a work situation
this
makes it practically impossible.

For the difference between P2 and P3 I think that things which do not
cause
this level of efficiency blow-out, but mean that a task takes twice as
long
or more, a P2 is justified.

A P3 should be solving a problem that is less significant than that.

I realise that these are rough figures, and working out how to apply
them
will still involve a measure of subjectivity, but maybe we can lessen it
somewhat. I think that would help us.

A second part of the proposal is to look at different tyypes of
requirements.
It seems reasonable to assume that a person with disabilities makes use
of
their software through the standard interfaces, so requiring special
skills
such as interpreting HTML source should not be considered as an access
method
in determining the impact of something. On the other hand, there are
peopole who can make use of such functions, which are after all common.
Although this represents perhaps 10% of the user community, makiing such
functions available is an important repair strategy. SInce it seems that
in
the near future no single strategy is going to solve everyone's
problems, we
should be prepared to include these things (view source is one example)
as
requirements, with their priority based on the difference they can make.
As
an example, if a user can look at the source of a document, and in
particular
of scripts, they can determine how to get access to a site that is
otherwise
completely inaccessible. (As sites I have used this technique for, there
is
the Boston "T" system - http://www.mbta.com, the first version of the
Sydney
Olympics Website, and others that I forget now). In other words, with
this
technique, access that was otherwise impossible becomes possible. So the
requirement is at P1 level - removing an (effectively) total barrier.

What do people think?

Charles McCN

--
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409
134 136
W3C Web Accessibility Initiative     http://www.w3.org/WAI    fax: +1
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Received on Tuesday, 20 March 2001 13:53:11 UTC