Based on the discussion so far, I would agree. The question probably needs some more analysis, since this is the first scale I have seen at least that breaks the Integer model. If we make it a new change request, we need to think carefully about how to deal with it, since it is possibly a breaking change. I say 'possibly' because in mathematical terms it is not; Reals are a more general kind of number than Integers. However, IT systems don't necessarily know that, so the question of exactly how existing data are represented and whether they will either a) seamlessly keep working if we change DV_ORDINAL to have a Real value or b) only require minor modificaitons to software. For example, if data are physically stored as XML, changing the relevant XSD field should enable the data to remain perfectly valid.
Clearly as more systems are built using openEHR, this kind of change would need to be very rare, but I think if a good impact analysis + implementation guidance is worked out, it could certainly be done now. I am interested in any arguments against it... - thomas On 26/04/2010 13:12, Mark Leaning wrote: > > Tom: > > The suggestion of making the numeric attribute real as opposed to > integer seems to me a pragmatic approach. > > Cheers > > Mark > > Mark S Leaning PhD** > > *From:* openehr-clinical-bounces at chime.ucl.ac.uk > [mailto:openehr-clinical-bounces at chime.ucl.ac.uk] *On Behalf Of > *Thomas Beale > *Sent:* 22 April 2010 18:45 > *To:* openehr-clinical at openehr.org > *Subject:* Re: ??? DV_CODEDQUANTITY > > The wiki one is interesting. Correspondences with openEHR (see > information model at > http://www.openehr.org/uml/release-1.0.1/Browsable/_9_0_76d0249_1109599337877_94556_1510Report.html): > > * nominal 'scale' - this is not really a scale, but a > classification concept, expressed using DV_CODED_TEXT > * ordinal scale - DV_ORDINAL > * interval scale - this is formalised by the abstract type > DV_ABSOLUTE_QUANTITY, whose only current subtypes are DV_DATE, > DV_DATE_TIME and DV_TIME. These types don't have + or - defined > in the normal way, although add and subtract operations > (different semantics do apply). > * ratio scale - this is formalised in the type DV_AMOUNT, which > models exactly the concept of quantities with a meaningful 0 > point and for which + and - operations are defined. Concrete > subtypes are DV_QUANTITY, DV_COUNT, DV_DURATION and DV_PROPORTION. > > this article doesn't seem to mention non integer 'ordinals' though... > > - thomas > > > On 22/04/2010 10:13, Mark Leaning wrote: > > This Wikipedia article is not bad: > http://en.wikipedia.org/wiki/Level_of_measurement > > > _______________________________________________ > openEHR-clinical mailing list > openEHR-clinical at openehr.org > http://lists.chime.ucl.ac.uk/mailman/listinfo/openehr-clinical -- Ocean Informatics *Thomas Beale Chief Technology Officer, Ocean Informatics <http://www.oceaninformatics.com/>* Chair Architectural Review Board, /open/EHR Foundation <http://www.openehr.org/> Honorary Research Fellow, University College London <http://www.chime.ucl.ac.uk/> Chartered IT Professional Fellow, BCS, British Computer Society <http://www.bcs.org.uk/> Health IT blog <http://www.wolandscat.net/> * * -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.openehr.org/mailman/private/openehr-clinical_lists.openehr.org/attachments/20100426/093a95f8/attachment.html> -------------- next part -------------- A non-text attachment was scrubbed... Name: ocean_full_small.jpg Type: image/jpeg Size: 5828 bytes Desc: not available URL: <http://lists.openehr.org/mailman/private/openehr-clinical_lists.openehr.org/attachments/20100426/093a95f8/attachment.jpg>
