On 18/03/2012 12:57, Grahame Grieve wrote: > Are discrete units only encountered in administrative directives? Do > you prohibit people from making observations or measurements that > include discrete units such as puffs, tablets, patches, vials, strips etc?
I don't think so; a physician could obviously ask a patient how many ventolin puffs they take a day. > > why? > > HL7 does because we claim that you have to have UCUM codes > so the data can be computable. If people simply want to exchange > it in a structured but non-computable fashion... they can go to hell. > And as for computable: we insist on a ucum code, and then say > that for these discrete unit kind of things, well, you just put "1" for > countable units, and then put the effective unit somewhere else - > somewhere that no one can actually pull off in practice - because > this is more "computable". Huh? We do not make sense on this. > > So much for HL7... what's openEHR's excuse? well it's not prevented from being expressed; it's just expressed using a Quantity field (e.g. a DV_COUNT) and another field saying what you are counting (there are a reasonable number of examples of this already in the archetypes - number of cigarettes a day, number of previous pregnancies, number of steps taken in physiotherapy etc). If we made this a Quantity, we could in theory then use an instance to say '3 puffs'. But this is not an amount of substance, it's a count of 'delivery' units or 'grains' of substance. I still think Quantities should be computable as such - if we don't know how many mcg of substance 3 puffs is, we can't compute with it. That's why it seemed to me that if we are going to try and bind this counting concept with a Quantity concept, then we need a dedicated subtype like DiscretisedQuantity that adds in the info of '3 puffs' to a Quantity that can represent '30 mcg'. - thomas
