Re: [Geopriv] Proposal for uncertainty

That speaks to keeping Section 3.3.  I am, as always, happy to accept
text suggestions.

Henning is right to identify the analogy to weather predictions.  This
is basic metrology, which is mercifully easier to grok than
meteorology.

On 27 May 2014 08:40, Rosen, Brian <Brian.Rosen@neustar.biz> wrote:
> No mechanism to collect location, especially civic location, is error free.
>
> There is a statistical probability a civic location supplied as “THE”
> location of some target is incorrect.
> It might be a small probability, it may be hard to calculate what it is, but
> there is some probability.
>
> With enough data, it IS possible to quantify the error.  I think we will be
> able to do that in environments like emergency calling.
>
> So, I’d like to see some language addressing the issue.
>
> Brian
>
> On May 23, 2014, at 8:48 PM, Roger Marshall <RMarshall@telecomsys.com>
> wrote:
>
> I would agree that getting everyone to agree on how they see probabilities
> used with civic addresses is a stretch.  Yet, the fact that the draft now
> allows for 100%, yet with cautionary language is a good thing to have.
>
> All the other changes looks good to me.
>
> Thanks Martin.
>
> -roger marshall.
>
> From: Henning G Schulzrinne [mailto:hgs@cs.columbia.edu]
> Sent: Friday, May 23, 2014 4:28 PM
> To: Martin Thomson
> Cc: GEOPRIV WG; Marc Linsner; Roger Marshall; Ray Bellis
> Subject: Re: [Geopriv] Proposal for uncertainty
>
> This is a reasonably-well known problem and seems similar to the "there is a
> 30% chance that it rains today" - it either rains, or it doesn't. The same
> can be said about a "home detection" algorithm that is based (for example)
> on some inferences (e.g., time of day and last GPS coordinates). In that
> context, it does make sense to say "there's an 80% chance that the caller is
> at home", which really means "in 80% of cases with the same amount of
> information, the person was indeed at home". It's relatively easy to
> calculate the weather case (although there's the rumor that weather
> forecasts over-predict rain since nobody complains if their BBQ does NOT get
> rained out), but probably hard for our case, given the lack of retrospective
> ground truth.
>
> Henning
>
>
>
> On Fri, May 23, 2014 at 4:12 PM, Martin Thomson <martin.thomson@gmail.com>
> wrote:
> 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/c2207408af95de74d1f4bb7d790965d69d4b3045
> 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.
>
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