Re: [Geopriv] Proposal for uncertainty

["Marc Linsner (mlinsner)" <[e-mail]>]

Martin,

IMO, the draft still confuses the term uncertainty, and I believe it¹s due
to trying to cover both geo and civic locations in the same draft.

S2: You define uncertainty as the results of limitations of measurement.

S2.3: You state that accuracy is a qualitative concept, hence not part of
the quantitative uncertainty concept.

S3.3: You (re)define uncertainty as accuracy/precision wrt civic.


WRT measured location, uncertainty goes down and confidence goes up as the
size of the polygon gets bigger (less accurate).  According to S3.3 wrt to
civic the opposite is true.  Is that what you are trying to say?

-Marc-




-----Original Message-----
From: Martin Thomson <[e-mail]>
Date: Friday, May 23, 2014 at 4:12 PM
To: GEOPRIV WG <[e-mail]>, Marc Linsner <[e-mail]>,
Roger Marshall <[e-mail]>, Ray Bellis
<[e-mail]>
Subject: Proposal for uncertainty

>I spoke about the one remaining issue with -uncertainty yesterday with
>Ray.  That conversation, along with Roger's comments regarding
>automated location determination helped me realize what I think the
>source of the disconnect here is.
>
>Based on this, I've tentatively concluded that the difference between
>civic and geodetic location is not what is at the core of the issue,
>though it's probably true that the issue only manifests with civic
>location information.  Primarily because of our better intuition
>regarding civic addresses.
>
>The core of the concern is that confidence - as a statistical measure
>- doesn't really make any sort of sense for location information that
>is a bald assertion, as opposed to locations that are generated by
>some measurement process (and here I give a nod to Carl for pointing
>out reverse geocoding as an example of a measurement process that ends
>with civic location).  For example, the assertion "I am at home" is
>verifiable and basically either correct or not, usually the former.
>
>It's only when taken in a larger context that terms like "confidence"
>even apply.  In particular, that means automated location
>determination.
>
>I've taken a stab at clarifying this in the draft.
>
>I've also permitted 100% confidence in the schema.  At the same time,
>I've retained the text describing this as impossible, but that text is
>all in the context of the statistical work, so I hope that the
>introductory material makes that clear enough.
>
>The changes are here:
>https://github.com/martinthomson/drafts/commit/c2207408af95de74d1f4bb7d790
>965d69d4b3045
>A readable copy is here:
>http://martinthomson.github.io/drafts/draft-ietf-geopriv-uncertainty.html
>
>Happy as always to take suggestions.  I'd like to think that this
>helps address Marc's concern without needing to cut Section 3.3
>entirely.