core terms: value/ unit
Chris Stoeckert
is cultured in 10% (volume/ volume) fetal calf serum or is up-
regulated 2-fold or is 3 days p.c. (post coitus) etc.
To do this we need numbers and units and relations as to how they were
determined - typically a measurement process.
We have the following relevant terms in OBI:
- measurement datum which is defined as an information content entity
that is a recording of the output of a measurement such as as produced
by an instrument. (Given the discussions on data/ datum this should be
relabeled as "measurement data item." )
- numeral which is defined as a symbol that denotes a number (from
IAO?). A symbol is a smallish, word like datum
- measurement unit label which is defined as a label that is part of a
measurement datum and denotes a unit of measure. (labels are a type of
symbol so it is of the same type as numeral).
- unit of a measure which is defined as the quality of some material
entity compared to which another quality is some multiple of. (one of
the sources is listed as 2000 years of philosophy which will make the
definition unrecognizable to biologists IMO).
In addition from the Units of measurement ontology that is under PATO:
- unit is defined as a standardized quantity of a physical quality.
Issues include:
how do we relate numerals and units to measurement data items. Can we
say that measurement data item has part numeral?
Do we use unit as a symbol or as a quality? I don't think we want
parallel representations of these.
If we say that the measurement data has quality unit of measure then
it gets us into the problem of dependent continuants having qualities.
I think we want to import unit (the root of the units of measurement
ontology) which I believe is a quality and should replace the current
unit of measurement in OBI.
Any ideas as to how to relate a unit quality to a numeral symbol and
measurement data item? How is this?
A mouse is on scale that reads out 5 grams.
The 5 grams is a recording of a measurement and constitutes a data
item. The information content of the data item is encoded as the
numeral 5. The quality that the measurement data item is about is
grams (which is a quantification of the quality of weight).
Cheers,
Chris