characters/states and measurements and other hoary problems
P. F. Stevens
peter.stevens at MOBOT.ORG
Thu Aug 3 14:43:36 CEST 2000
>A couple of points.
>With regard to footnote 1.
>1 Attribution and sources for an item datum overides that for a character or
>taxon, which override that for the treatment as a whole. Attribution for
>characters and taxa are equivalent and additive.
>Don't we also need to say that item data attribution at the specimen level
>may override that for a character or taxon as a whole? Otherwise, the system
>has no way of dealing with misidentifications, particularly if some but not
>all parts have been associated with the wrong ID, as might be frequently
>encountered in fossils, or when dealing with taxa whose character state
>definitions are later found applicable for only a specific size range (ie
>differentially break down at small sizes). Specimen or parts level
>data/attributions also would presumably be additive, even if potentially
>contradictory (subject to differences of opinion), would they not?
This seems a reasonable point .
>If we are to presume nested levels of groupings of descriptor elements, then
>we need to be able to clearly distinguish data values that are regarded as
>referring to "individual units" (specimen, species, higher level taxon) at
>one level, but are "collective" when evaluated at a different level. Not
>only with the "collation rules" be different for different levels, but may be
>different depending on whether a given feature (possibly "same feature but
>defined differently") is regarded as a data item refering to a specific
>"individual unit", or as a "collective unit". That is, the data item is a
>representation of data that might apply to a collection, rather than a
>measurable value that may have a scope no larger than a specific measure of a
>specific specimen. Perhaps some treatments might include "collections of
>collections" that would imply a mixing of both situations.
I presume you mean
Specimen with ID - set of individual measurement or set of measurements
(say in mm.) all associated with this specimen (maybe at a particular
Specimens of species: grouped, a larger series of measurements, and/or
variously processed (e.g. mean + s.d.)
the measurement(s) of either the specimen or the species could be assigned
to states; those states might encompass a range of variation such that the
attributuion of a specimen/species to that state would mean that, when
refering to the state, one loses sight of the original measurements.
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