In a message dated 10-2-2009 15:56:17 W. Europe Standard Time, thomas.beale at oceaninformatics.com writes: > *theoretically speaking, such 'quantities' are not true quantities - a > true quantity is one that states the amount of some physical substance > or flow, and by definition has units to measure that. Pain and other > scores are not true quantities, they are just numbers. True quantities > have the operations +and - defined on them. I doubt that pain scores > could be meaningfully added for a single individual, let alone across > individuals. > > However ... the current specification allows DV_QUANTITYs to have an > empty unit string, which allows for these pseudo quantities that are not > modelled as Ordinals. We really should not do this. Instead we should > have an equivalent of DV_ORDINAL that allows fractional values - > Ordinals only have ordered, but math operations are not defined on them. > DV_SCORE might be an appropriate addition to openEHR. > > - thomas beale > > *
Thomas, Thank you for your reply, however it does not satisfy the request. I think that the pain score is indeed not a physical measurable instrument. But it is not an Ordinal, in statistical terms it is an Interval if the numeric score is used (0, 1, 2, 3 etc up to 10) and a ratio when the VAS scale is used. Hence reliability studies have determined that it is useful in practice. However, I would like to have the following DV_PhysicalQuantity meeting the PQ requirements from ISO 21090 and the DV_CodedOrdinal, or DV_Ordinal meeting the requirements for the CO (Coded Ordinal) from ISO 21090. The CO does allow the order as we need, and allows the mathematical operations such as summations, calculations like BMI style, among others. Sincerely yours, dr. William TF Goossen director Results 4 Care b.v. De Stinse 15 3823 VM Amersfoort the Netherlands email: Results4Care at cs.com phone + 31654614458 fax +3133 2570169 www.results4care.nl Dutch Chamber of Commerce number: 32133713 -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.openehr.org/mailman/private/openehr-technical_lists.openehr.org/attachments/20090210/ffa52223/attachment.html>
