VEP6: blurry definition for the term #calibration

[Paul Harrison]

> On 2021-03 -27, at 12:01, Paul Harrison <paul.harrison at manchester.ac.uk> wrote:
> 
>> On 2021-03 -26, at 15:30, Markus Demleitner <msdemlei at ari.uni-heidelberg.de <mailto:msdemlei at ari.uni-heidelberg.de>> wrote:
> 
>> So, you're basically proposing in addition to the four options at the
>> foot of
>> 
>>  http://mail.ivoa.net/pipermail/semantics/2021-March/002778.html <http://mail.ivoa.net/pipermail/semantics/2021-March/002778.html>
>> 
>> to have 
>> 
>> (e) declare that #progenitor and #calibration are disjunct by
>> changing #progenitor's definition to "it's only... hm... 'science
>> data'", and any sort of calibration data is outside of the provenance
>> chain.
>> 
> 
> No - I would go for a modification of your option b) and add another child of #progenitor, perhaps #antecedent - though in natural english
> I think that they are virtually exact synonyms - that expresses that the file is a direct “less processed data” #progenitor in the sense of my distinction that #calibration is a modifier of rather than a “direct ancestor”, so that #calibration and #antecedent are disjunct.

I have thought about this proposal a little more, and It seems that when trying to satisfy the two use cases

* distinguish between “science” data and “calibration” data
* distinguish between used calibration data and alternative calibration data

We tend to get contradictions occurring, which leads me to think that we have to drop one of the use cases - the one that I would drop is distinguishing between used and alternative calibration data, because I think that in most simple scenarios of assessing data quality it is most important to understand what “kind” of data you are looking at to give you an impression of how well the instrument was performing. Which of the possible calibration data were used should be the domain of ProvDM.

I had promised to do an alternative VEP, but I thought that I would try to flesh things out here a little more before doing that, because I can see that there are aspects that people are not going to like. 

The consequence of #progenitor meaning “was involved in the creation of #this" implies that anything marked #calibration was used i.e. it is not possible to tag alternative calibration data with #calibration. I would accept this limitation as I think it is probably more important to know what was actually used rather than what could be used, in this “quick look” scenario that the data-link vocabulary is designed for.

The problem with the hierarchy approach for the advocates of wanting to distinguish between science data and calibration data is that it is perfectly possible for a data provider to just tag both #calibration and #antecedent data with #progenitor and then the distinction is lost. This possibility does make option e) above much more attractive as a way of forcing this distinction, and at the moment I am wavering as to whether that is my favourite…It does have the advantage that if suitably defined it could encompass “used” or “alternative” as it is not a child of #progenitor.

Paul. 



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