I think the fact that some results are a mean calculated by a human is a red-herring. In fact nearly all numerical analyte values from automated machines are a mean of a number of estimates - part of the internal quality control is that the standard deviation of these estimates is "acceptable" - this is just "hidden under the hood".
Some systems certainly record a value of 0, instead of, or in a addition to, zero RBC per HPF. How many HPF's are examined and acceptable values for the SD when done manually are all part of the "analysis technique" used and not generally stored in the patients paper record, let alone EHR. Regards Vince Vincent McCauley MB BS, Ph.D ----- Original Message ----- From: "Tim Churches" <tc...@optushome.com.au> To: "Tim Churches" <tchur at optushome.com.au> Cc: "Sam Heard" <sam.heard at bigpond.com>; "Openehr-Technical" <openehr-technical at openehr.org> Sent: Thursday, October 23, 2003 17:25 Subject: Re: Re: Pathology requirements TEXTURAL RESULTS TO QUANTITIES > Tim Churches <tchur at optushome.com.au> wrote: > > > > Sam Heard <sam.heard at bigpond.com> wrote: > > > > > > TEXTURAL RESULTS TO QUANTITIES > > > > ?TEXTUAL? > > > > This raises the general issue of how mixed categorical/ordinal/scalar > > quantities > > are handled eg (made up example) haematuria: Trace->x RBC/ml -> Gross > > > > haematuria. > > Sorry, brain-fade. I meant x RBC/HPF (per high power field) or similar. This is an > example of a sampled result i.e. a random sample of portions of a "specimen" > are examined and a mean is reported. The mean is quantitative, but is just a > point estimate of the central tendency of an underlying probability density > function. Thus it may have a std dev or confidence intervals associated with it. > Also, in this circumstance zero doesn't really mean zero and is generally not > reported as such: if no RBC were seen in any HPF, then it will be reported > as "No RBC seen", not as "mean RBC/HPF = 0". Generalising this, scalars > which parameterise a probability distribution are different from scalars which are > precise quantities - or are they? Hmmm. > > Tim C > > > > Conceivably some use might be made of the numbers, as > > opposed > > to the ordinal categorical extrema? > > > > Tim C > > - > > If you have any questions about using this list, > > please send a message to d.lloyd at openehr.org > > - > If you have any questions about using this list, > please send a message to d.lloyd at openehr.org > > - If you have any questions about using this list, please send a message to d.lloyd at openehr.org
