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Re: AW: ISSUE-31 (Aggregation): Supporting aggregation for other than SKOS hierarchies [Data Cube Vocabulary]

From: Dave Reynolds <dave.e.reynolds@gmail.com>
Date: Thu, 17 Jan 2013 14:34:55 +0000
Message-ID: <50F80C0F.4020400@gmail.com>
To: Benedikt Kaempgen <kaempgen@fzi.de>
CC: "public-gld-wg@w3.org" <public-gld-wg@w3.org>
Hi Benedikt,

On 11/01/13 13:04, Benedikt Kaempgen wrote:
> Hello,
>> For Data Cube, of course, the issue is not whether those relationships
>> can be represented (they can already [1]) but whether Data Cube
>> dimensions can reference and reuse those representations directly.
> I am wondering why it would not be sufficient to recommend publishers to add skos:narrower and skos:broader relationships - if semantically applicable - to the domain specific properties. I see your point that with time and geo there might be many possible values to the dimensionProperties; however, in general, the number of possible values of a dimensionProperty (especially as used by a certain dataset) is small in comparison to the number of observations. Thus, I would not see a problem in adding the needed triples to the same file as the data structure definition.

There are at least two issues with that.

First, the publisher of the geography and the publisher of the 
statistics themselves are often (at least in our case) different. So 
requiring, for example, a local authority to publish a set of assertions 
about the Ordnance Survey's administrative geography URIs just in order 
to publish their own local statistics would be ... problematic.

Secondly, it's semantically dubious. The correct hierarchical 
relationship for statistical geographies in this case is containment 
which is different from skos:narrower/broader. This was already 
discussed up-thread.

> Is there a concrete use case that would require direct usage by QB?

Several authorities in the UK including the Department for Communities 
and Local Government and the Welsh Assembly Government have published 
"index of deprivation" data using QB and using geographic linked data 
from the Ordnance Survey. In each case the people publishing the data 
(not us in either of those cases) raised the question of how they could 
use the published geographic containment information as the hierarchy 
definition for the cubes.

[This is the same concrete use case already recorded in the issue.]


> In any case, I have added a requirement "There should be a recommended mechanism to support non-SKOS hierarchical code lists" to [1].
> Best,
> Benedikt
> [1] <http://www.w3.org/2011/gld/wiki/Data_Cube_Vocabulary/Use_Cases#There_should_be_a_recommended_mechanism_to_support_non-SKOS_hierarchical_code_lists>
> ________________________________________
> Von: Dave Reynolds [dave.e.reynolds@gmail.com]
> Gesendet: Samstag, 18. Februar 2012 13:34
> An: public-gld-wg@w3.org
> Betreff: Re: ISSUE-31 (Aggregation): Supporting aggregation for other than  SKOS hierarchies [Data Cube Vocabulary]
> Hi Dan,
> Fully agree that there are distinct semantic relationships.
> For Data Cube, of course, the issue is not whether those relationships
> can be represented (they can already [1]) but whether Data Cube
> dimensions can reference and reuse those representations directly.
> As you might expect my proposed answer is that indeed we should be able
> to use such existing representations directly, for example by annotating
> a Dimension with information on the properties used to represent the
> hierarchy.
> Dave
> [1] For sub-type/super-type we have rdfs:subClassof. For meronomies then
> there are a number of both generic and domain-specific ontologies for
> representing part-whole relations. Furthermore OWL2 gives power (for
> those who need it) to axiomatize part-whole relations.
> On 17/02/12 18:48, Gillman, Daniel - BLS wrote:
>> Dave,
>> I have a short comment on this one for now.  Relying on the SKOS relations of broader / narrower to express hierarchies is semantically limited.  There are 2 main kinds of hierarchical relations: generic and partitive.  Both should be available for use.  The broader / narrower constructs in SKOS subsume both, yet they are quite different.
>> Generic refers to the super-type / sub-type relation.  An example is the relationship between vehicle and automobile.  An automobile is a vehicle, but not every vehicle is an automobile.
>> Partitive refers to the part-whole relation.  An example is the relationship between an automobile and the engine.  The engine is a part of an automobile, but it is not an automobile itself.
>> The ISO standards 704 and 1087-1 describe this very well.  SKOS references ISO 2788, but that standard is imprecise in this matter.
>> You mentioned SDMX in the statistical community.  The other important metadata standard in use there is the DDI (Data Documentation Initiative), and an effort out of DDI work is to extend SKOS to include a richer semantics as I described above.  This is being called XKOS.  Richard is involved.
>> Yours,
>> Dan
>> Dan Gillman
>> Bureau of Labor Statistics
>> Office of Survey Methods Research
>> 2 Massachusetts Ave, NE
>> Washington, DC 20212 USA
>> Tel     +1.202.691.7523
>> FAX    +1.202.691.7426
>> Email  Gillman.Daniel@BLS.Gov
>> -----------------------------------------
>> "Whatever it is, I'm against it!
>> No matter what it is or who commenced it,
>> I'm against it!"
>> ~ Groucho Marx
>> ------------------------------------------
>> -----Original Message-----
>> From: Government Linked Data Working Group
>> Issue Tracker [mailto:sysbot+tracker@w3.org]
>> Sent: Friday, February 17, 2012 11:14 AM
>> To: public-gld-wg@w3.org
>> Subject: ISSUE-31 (Aggregation): Supporting aggregation for other than SKOS hierarchies [Data Cube Vocabulary]
>> ISSUE-31 (Aggregation): Supporting aggregation for other than SKOS hierarchies [Data Cube Vocabulary]
>> http://www.w3.org/2011/gld/track/issues/31
>> Raised by: Dave Reynolds
>> On product: Data Cube Vocabulary
>> Data Cube, like SDMX, supports a notion of hierarchical dimensions.
>> For example, a data set on population might be broken down by sex. If the code list is hierarchical (with an ex:ALL top category with subcategories of ex:Male and ex:Female) then it is possible to publish a dataset with the overall population corresponding to the top level code (ex:ALL) and then the number of men and women coded against the sub-categories. In the current design skos:Concepts are used for such code list and thus skos:broader/skos:narrower used to define the hierarchy.
>> Do we need to generalize or clarify this mechanism?
>> Specifically:
>> (1) Should Data Cube allow non-SKOS hierarchical code lists? E.g. by declaring the property which links codes into a subsumption hierarchy.
>> A specific use case for this is for geographic information. Many statistical data sets published by governments include dimensions of time (sdmx:refTime) and area (sdmx:refArea). For representing geographic or administrative regions there are large existing linked data sets (such as http://data.ordnancesurvey.co.uk/.html) where the spatial containment relation has already been defined and is not skos:narrower. Similarly for representing time periods like Quarters, Half (Government) years etc there are services such as the UK reference time service (http://www.epimorphics.com/web/wiki/using-interval-set-uris-statistical-data). Can those hierarchies be directly used for Data Cube dimensions?
>> See also discussion thread at [1].
>> (2) Should it be possible to explicitly provide an aggregate value at the level of a qb:Slice?
>> A specific use case for this publication of financial data. Some UK local authorities have published payments information using a Payments ontology[2] which derives Data Cube. Individual expenditure line times appear as single qb:Observations, these are then grouped into qb:Slices which make up a single payment and the total payment is given at the slice level. This may be a common pattern which, if support directly by Data Cube, would allow for publication of aggregates which cross multiple dimensions.
>> The possible ways of expressing such aggregation relations is related to ISSUE-30.
>> [1] http://groups.google.com/group/publishing-statistical-data/browse_thread/thread/dc8d7e231d47935e/b3fd023d8c33561d?#b3fd023d8c33561d
>> [2] http://data.gov.uk/resources/payments
Received on Thursday, 17 January 2013 14:35:28 UTC

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