W3C home > Mailing lists > Public > public-wai-ert@w3.org > April 2005

Re: Another comment about confidence value.

From: Charles McCathieNevile <charles@sidar.org>
Date: Tue, 19 Apr 2005 19:54:28 +0200
To: "Paul Walsh" <paul.walsh@segalamtest.com>, "'Nils Ulltveit-Moe'" <nils@u-moe.no>
Cc: "'Giorgio Brajnik'" <giorgio@dimi.uniud.it>, public-wai-ert@w3.org
Message-ID: <op.sphqo2klw5l938@researchsft.pwlan-swisscom-mobile.ch>

On Tue, 19 Apr 2005 11:32:01 +0200, Paul Walsh  
<paul.walsh@segalamtest.com> wrote:

(I think this bit was Nils - CMN)
> I appreciate that. With such a profile your testers would most probably
> be quite confident in their decisions, and if you are 100% confident
> that an accessibility issue is real, then the extra confidence value is
> not needed. (i.e. the default value for confidence, if it is left out,
> is 1).

> [PW] Every 'validation' company needs to follow the same process
> irrespective of experience. That way, the output of the 'team' will be
> 100 confident in their interpretation of the checkpoint passing or
> failing. If they are not, then you have an issue with that company's
> capabilities and/or understanding of the checkpoints.

This is why I want to have a variety of confidence datatypes. In principle  
you would have one per test process, but in practice there are going to be  
lots of overlaps - for example if 100 different tests, run according to  
Nils' process, give probability results accurate to 2 significant figures,  
then it is probably OK to use the same datatype for all of them

On the other hand if I use a different process for a similar test, and its  
results are different, I should use a different datatype. That way it is  
possible to compare the results more accurately if I know more about the  
differences in how the confidence is generated. The sort of examples that  
spring to mind are to do with the accuracy of meters, or of labelling on  
resistors, not WCAG conformance. For WCAG I think these comparisons, and  
for that matter many confidence level sets, are going to be based on  
smaller sets - High medium low, integer from 1 to 7, etc.

I suspect I still haven't made this very clear. Any hints?



Charles McCathieNevile                      Fundacion Sidar
charles@sidar.org   +61 409 134 136    http://www.sidar.org
Received on Tuesday, 19 April 2005 17:54:52 UTC

This archive was generated by hypermail 2.4.0 : Friday, 17 January 2020 17:52:49 UTC