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values and datatypes Re: Another comment about confidence value.

From: Charles McCathieNevile <charles@sidar.org>
Date: Tue, 19 Apr 2005 20:15:06 +0200
To: "Nils Ulltveit-Moe" <nils@u-moe.no>
Cc: "Giorgio Brajnik" <giorgio@dimi.uniud.it>, public-wai-ert@w3.org
Message-ID: <op.sphrngm3w5l938@researchsft.pwlan-swisscom-mobile.ch>

On Mon, 18 Apr 2005 21:07:31 +0200, Nils Ulltveit-Moe <nils@u-moe.no>  

> Hi Charles,
> I would suggest that confidence is interpreted as it is defined in
> statistics; i.e. as a probability which is a real number from and
> inclusive 0 and to and inclusive 1.
> Using the probability is a generally accepted way of representing
> confidence values in most areas of science. Other representations can be
> derived from this.

Well, if the probability can be statistically determined (which happens  
often enough for it to be considered a useful convention) this makes  
sense. But, for example, the kinds of confidence that people are talking  
about when looking at alt text values are really pretty random - certainly  
not accurate to 1 whole significant figure.

These could be refined over time by applying machine-learning principles  
to a large setof human-monitored results, giving something statistically  
more useful.

But starting from where we are now, I think that we need some wayto say  
that one setof confidence values doesn't necessarily map cleanly to  
another one, and it seems to me that datatypes are a good way to do that.

It might be sensible to define a datatype that is a probability value, and  
tell people that unless they are applying a known algorithm with known  
means of determining confidence they should subClass it for the datatype  
of their confidence. Which brings us back to the issue that we have to  
wait a little longer to get the best ideas of the best RDF developers on  
the best way to define datatypes...



Charles McCathieNevile                      Fundacion Sidar
charles@sidar.org   +61 409 134 136    http://www.sidar.org
Received on Tuesday, 19 April 2005 18:15:22 UTC

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