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Re: Understanding Terms and Services

From: David Singer <singer@apple.com>
Date: Fri, 09 Mar 2012 10:48:20 -0800
Cc: Karl Dubost <karld@opera.com>, "Chappelle, Kasey, VF-Group" <Kasey.Chappelle@vodafone.com>, "public-privacy (W3C mailing list)" <public-privacy@w3.org>
Message-id: <E4CA2C0A-30F9-47FB-B1E5-9C1D17039BC2@apple.com>
To: Dan Brickley <danbri@danbri.org>

On Mar 9, 2012, at 8:36 , Dan Brickley wrote:

> On 9 Mar 2012, at 17:27, Karl Dubost <karld@opera.com> wrote:
>> Le 9 mars 2012 à 10:52, Chappelle, Kasey, VF-Group a écrit :
>>> there's no real privacy impact on you personally
>> Define this :)
>> How do you know that?
> The term 'Aggregate' is too vague - 'oh, we aggregated by country',  or even 'by city' isn't universally reassuring.

It's too vague in two important respects:

1) aggregation with what granularity? - as you say.   Zip-code specific, combined with a few other facts, is pretty revealing.

2) More critically, 'aggregation' is ambiguous over (at least) the following two practices
2.a) We keep separate counts for how many visitors fall into various aggregate counters: male/female, age-range, geo area, and so on.  "We had 25,000 men, 2,000 people from San Francisco, and 8,000 over-60's, visit us" does not enable anyone to find out whether there was a single over-60's San Francisco man (except statistically).
2.b) We keep records that, per visitor, record the linkage "an over-60's man from San Francisco", and so on;  we then can derive the counts in 2.a.

2.b is what is used if you want to do product-prediction - "people who bought A also often bought B, C" as the linkage is critical.  But these are now per-user records, and as such, amenable to de-anonymization. For *me* these are anonymized records, not aggregated - I would reserve 'aggregated' for 2.a - but I think that this ambiguity exists.

David Singer
Multimedia and Software Standards, Apple Inc.
Received on Friday, 9 March 2012 18:48:49 UTC

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