- From: Andrea Perego <andrea.perego@jrc.ec.europa.eu>
- Date: Sun, 10 Apr 2016 00:36:38 +0200
- To: Antoine Isaac <aisaac@few.vu.nl>
- Cc: "public-dwbp-wg@w3.org" <public-dwbp-wg@w3.org>
Thanks a lot, Antoine. My comments inline. On 08/04/2016 15:36, Antoine Isaac wrote: > Hi Andrea, > > Some time has passed since that last email. > I'd like to have a quick check before we close a number of actions > such as > https://www.w3.org/2013/dwbp/track/actions/262 +1. Thanks! > Of notable interest for this discussion: > > - the latest version for the section on conformance > http://w3c.github.io/dwbp/vocab-dqg.html#ExpressConformanceWithStandard > > - updated diagrams showing the relations between metrics, annotations, > policies, etc. > http://w3c.github.io/dwbp/vocab-dqg.html#model Thanks again, Antoine. I checked the new specification, but I'm afraid I have to study it more thoroughly to have a good enough understanding of its use. The examples are very helpful, but of course they cannot cover all the use cases. So, I wonder whether you can help me understand one issue. I see (fig. 2) that the "circle" has been closed with prov:wasDerivedFrom. However, it is not completely clear to me how/whether it is possible to state that a resource *does* not conform to a given standard / quality policy. E.g., by using dqv:QualityAnnotation I can specify the tested resource (oa:hasTarget) and the result of a conformance test (oa:hasBody), but then I miss how I can state that the conformance test has been carried out against a given standard / quality policy. Overall, what is not completely clear to me is whether DQV has a kind of "expanded" representation of dct:conformsTo (on the lines of the Dublin Core to PROV mapping). Best, Andrea > Cheers, > > Antoine > > On 3/10/16 12:01 AM, Antoine Isaac wrote: >> Hi Andrea, >> >> No problem with long mails, as long as they give the opportunity for >> productive discussions! >> And I believe this is the case here. And like, as in *hugely* productive. >> >> First I'm going to add a reference Issue-202 so that our tracker can >> keep tracking: >> https://www.w3.org/2013/dwbp/track/issues/202 >> >> Second I'm noting this becomes marginally related to conformance >> levels. It's more about conformance statements in general. I guess >> we'll come back to levels later... >> >> Now I'm going to try and answer your points: >> >> >> On 3/8/16 2:31 PM, Andrea Perego wrote: >>> Hi, Antoine. >>> >> [snip] >>>> - we are about to add in DQV examples regarding quality policies (draft >>>> at [1]). Do you think this is closely related to the issues you raised >>>> here? Should we unify the patterns? At this stage I'd rather avoid the >>>> extra work, but I do have to check with you. >>>> >>>> [1] >>>> https://www.w3.org/community/odrl/wiki/W3C_Data_on_the_Web_Best_Practices_-_Data_Quality_Policy >>>> >>> >>> Yep - I think it's definitely related to the scenarios I was >>> referring to. >>> >>> If I correctly understand, the idea in [1] is to use ODRL to provide >>> a formal description of a quality policy (in this case, an SLA). >> >> >> Yes. >> >> >>> So, the computed quality measurements can be matched against what >>> said in the quality policy (_:ex1) to determine whether the relevant >>> resource (:myDatasetDistribution) complies with it >>> (:myDatasetDistribution dct:conformsTo _:ex1). >> >> >> We had not touched the problem yet. But of course it should be >> possible to (numerical) quality measures correspond to tests for >> checking conformance with SLAs or other policies. Especially when the >> quality dimensions are relevant for SLAs. >> >> >>> >>> Quality measurements and conformance statements could be both seen as >>> "observations" (in the broader sense), so aligning their >>> representation shouldn't be a problem, conceptually. >> >> >> Agreed. This would be desirable, even. >> >> NB: before continuing, I'm going to assume familiarity with the >> current DQV patterns: >> http://w3c.github.io/dwbp/vocab-dqg.html#model >> >> >>> However, I don't know if the current version of DQV can already >>> support this.In particular, two points are unclear to me: >>> >>> 1. Can dqv:QualityMeasure be used to express a conformance statement? >>> >>> This would require, e.g., expressing the quality measure "value" >>> (dqv:value) with code lists as those used in ISO, EARL and INSPIRE. >>> However, in the examples currently included in DQV, dqv:value is used >>> only with literals. >> >> >> Yes. And I think the idea (which is also the one of daQ) is that we >> keep Measurements to numerical values, generally. This also gives some >> benefits related to interoperability with RDF Data Cubes. >> >> If there's a quality observation that is more 'semantic' (e.g. with a >> controlled vocabulary) I'd expect it is rather done with >> QualityAnnotations, not QualityMeasurement >> That being said I believe we can have some alignments (see below). >> >> >> >>> >>> On this issue, it is worth mentioning the ISO approach: >>> https://geo-ide.noaa.gov/wiki/index.php?title=ISO_Data_Quality >>> As you can see from the UML diagram, ISO has the notion of data >>> quality report (DQ_Element), where the result can be either a >>> quantitative result (DQ_QuantitativeResult) or a conformance result >>> (DQ_ConformanceResult). As far as I can see, dqv:value models just >>> the former (quantitative result). >> >> >> Right. >> >> In DQV now the final conformance statement could be either expressed >> as dcterms:conformsTo or QualityAnnotations. >> I think what we originally meant was to reflect differences of >> 'authoritativeness' for the conformance statement. We (at least I, at >> the time) felt that publishers of datasets should be allowed to >> express their conformance statements in a more direct way than >> agencies or just any user (and here the difference of authority could >> be more obvious) 'tagging' the dataset as being conformant. >> >> But in the light of the discussion we had together these last days, >> I'm now tempted to accept that there is some mapping between both, as >> you do with GeoDCAT-AP. The difference would just one of granularity... >> >>> >>> >>> 2. Which is the relationship between dqv:QualityMeasure and >>> dqv:QualityPolicy? >>> >>> I don't know if this is already supported, but I think that an >>> explicit relation between these entities will "close the circle" >>> between two relevant branches of DQV, making it possible to align the >>> representation of quality measures and conformance statements. >>> About "closing the circle", but on a different part of DQV: >>> Is there any relationship between dqv:QualityAnnotation, >>> dqv:QualityMeasure and dqv:QualityPolicy? This would allow the >>> association of a quality annotation (e.g., in the form of a quality >>> certificate) with the computed quality measures, demonstrating >>> conformance with a given quality standard (e.g., the ODI certificate). >>> >>> >> >> In fact the loop may be closed by the other discussion we have about >> Issue-222 on 'derived metrics', with relations like 'dependsOn', >> 'isUsedToObtain', 'wasInfluenceBy'... [1,2] >> If we generalized the relations discussed there to be applicable to >> other classes than Metric or QualityMeasurement, we could express that >> a QualityAnnotation or QualityCertificate is based on a QualityMeasure. >> >> I think this could go a long way meeting your requirement. What do you >> think of this? >> >> If you agree then we would modify the scope of Issue-222, to make sure >> the outcome of that one can be used for closing the loop! >> >> Cheers, >> >> Antoine >> >> [1] https://lists.w3.org/Archives/Public/public-dwbp-wg/2016Feb/0045.html >> [2] https://lists.w3.org/Archives/Public/public-dwbp-wg/2016Mar/0026.html >> >> -- Andrea Perego, Ph.D. Scientific / Technical Project Officer European Commission DG JRC Institute for Environment & Sustainability Unit H06 - Digital Earth & Reference Data Via E. Fermi, 2749 - TP 262 21027 Ispra VA, Italy https://ec.europa.eu/jrc/
Received on Saturday, 9 April 2016 22:37:22 UTC