GarryJolleyRogers - Wed Nov 25 2009 - Version 1.13
Parent topic: ClosedTopicSchemaDiscussionSDD09
The 0.9 permits a character value to have both a State and a
(example: generally blue except when 4.0 ??? )
-- Main.BobMorris - 09 Mar 2004
Surely the only statistic that would sensibly apply to a state is a frequency (e.g. blue @95%, red@5%) - but this is handled elsewhere is it not?
-- Main.KevinThiele - 10 Mar 2004
Ah, I was thinking of the state applying to the statistic, not the statistic applying to the state. I wonder if this distinction is important.
No, wait, I was thinking of both the state and the statistic as applying to the character.
I wonder if these discinctions are important...
-- Main.BobMorris - 10 Mar 2004
The latter (both state and statistic apply to character) is present in 0.9. Kevin's scenario is handled by the Frequency modifiers.
I have two scenarios for allowing a character to have both categorical and numeric (and, derived from that, statistical) data:
1. counts are often counted, but treated categorical ("many") when a certain threshold of "practical countability" is reached. This can occur within a single dataset.
2. When combining data from different sources, incl. your own observations you will often have a mixture of categorical expression (legacy flowers: "less than 1 cm", "1-2 cm", "2-3", "larger than 3 cm") and statistical measures (mean = 2.3 cm) and your own repeated measurements (2.0, 2.5, 2.2, 2.1) from which the mean is automatically calculated.
These scenarios are real, but I am happy for any criticism whether the current parallelism that I introduced is the best solution for the problem. The way it is handled in DELTA is to have two characters.
Bob's example: "wings generally blue except when more than 4.0 cm long" is actually a second problem. It expresses a relationship between two characters -- and we currently have no means implemented in SDD to describe objects through such logical expressions or knowledge. We have only means of enlisting factual observations. So, do we need this additional power?
We do already experience this need in the Key/*/Lead/CodedStatements expression when linking the unconstrained language of key-statements to states in the terminology.
-- Gregor Hagedorn - 12-16 Mar 2004
So:
The most interesting question is Gregor's latter example of a logical restriction on a state when a condition is met - an IF-THEN statement. These are surprisingly common, particularly in dichotomous keys.
I've wondered how to handle such contingencies in Lucid - in fact this is exactly the ContingencyProblem that bedevils matrix-based keys. I'd really like a solution for this one (but not for SDD1.0!).
One obvious issue is that the contingency applied needs to tie in several states - that is, the obvious question when faced with "wings generally blue except when more than 4.0 cm long" is "so what colour are they when less than 4 cm long?" We need IF-THEN-ELSE statements, surely (although these will be too restrictive also to help in real circumstances).
-- Main.KevinThiele - 22 Mar 2004
As a final note to the above: In versions after 0.9, character is now treated not as a real abstract entity, but as a concrete variable that has a single possible data type. The advantage is that the character matches directly to data analysis, the disadvantage is that data integration of numerical and categorical data for the same abstract entity (e.g. leaf length) are less obvious. However, since they are defined in the mapping sections, they can be obtained from the terminology.
-- Gregor Hagedorn - 5 July 2004