Nested character states

Jaan Palisaar jpalisaar at GMX.DE
Tue Sep 18 13:51:55 CEST 2001


Dear Mike Dallwitz,

I will send a copy of the program directly to your adress (anybody else 
interested just drop me a short line; but be warned: it's entirely in 
german).

You are of right that you can achieve a similar effect by using 
dependencies, but as far as I can see you will get a huge number of 
characters (please correct me if I'm wrong, but as I understand you can 
only define dependencies between characters, not between character 
states) with many character states which can be very confusing. Being 
able to nest the characters would be - I believe - much more intuitive 
and could save a lot work when coding the items.

Just to give one example: habitat or substrate (in case of epiphytes) is 
often an extremely useful character (does it live in woodland or in the 
open? In grasslands or arable fields? Wet or dry grasslands? Acid or 
calcicolous grasslands? If you code a species as living in acid 
grasslands but your end-user just remembers (or the herbarium lable only 
states this) that he found it in the open, he will be lost. But if you 
defined acid grassland as a subset of open lands the species will still 
be included. And entering data should be easier since once you defined 
the hierachy of character states you only have to enter a low level 
character state and have everything above automatically included.

This is probably nothing which couldn't be achieved with clever use of 
dependencies and an intelligent ID program but to me it seems more 
intuitive.

Again, I'm still new to DELTA and what it can do, so maybe I just 
haven't discovered all it's abilities or try to invent the wheel anew. 
In any case, thanks for your comments

Jaan Palisaar

Jaan Palisaar
AG Naturschutz II, FB Biologie
Philipps University Marburg
35032 Marburg

e-mail: palisaar at mailer.uni-marburg.de



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