Tim Churches wrote: > Thomas Beale wrote: > >> Concerning my last reply on this subject, >> >> I feel the appropriate solution is: >> * add an attribute value_qualifier of type STRING with allowable values >> >>> , <, >=, <=, = (since this is a closed list, using coded terms doesn't >>> >> seem to be useful) >> * allow ELEMENT.null_flavour and DV_QUANTIFIED.accuracy to be used to >> cover Vince's Inaccurate (probably wrong) and '~' (slightly inaccurate, >> but usable value) cases respectively. In the latter case, it seems to me >> that if accuracy is going to be reported, it should be quantified, the >> way we do it in openEHR, i.e. +/- 5%, +/-2 and so on. Vince - am I being >> unreasonable? Did you have '~' because labs devices output this? >> > > If you are going to capture error limits around a scalar quantity, then > you need to also capture the nature of those limits. Sometimes they are > simply co-efficients of variation, sometimes one or two (or 1.96) > standard deviations (as frequentist confidence intervals for normally > distributed data, or asymptotically normal confidence limits for > non-normally distributed data), sometimes they are non-normal confidence > limits, and occasionally (but often with clinical trials etc) they are > Bayesian credible intervals. Then there is the confidence level - often > 95% but sometimes 99%, sometimes less. Will the proposed solution cover > these and other scenarios? > Hm....that's a good question. Currently the model (see http://www.openehr.org/uml/Browsable/_9_0_76d0249_1109599337877_94556_1510Report.html) only captures limits as either a +/- percent, or as a +/- absolute value (see the accuracy attributes in the diagram) - it does this via the attribute accuracy_is_percent which is just a Boolean. What you are asking for would be accommodated by making it a code which indicated the meaning of the accuracy band.
So far we have not had such requirements expressed for the openEHR models, but as I happen to know you are coming form an epidemiological/public health/statistical point of view, clearly we need to accommodate them. Tim, if the accuracy_is_percent attribute was upgraded to a coded value, could you suggest a set of meanings that would cover all the epi/PH needs? - thomas
