Hello!
I would like to have people’s opinions on the following:
We are building a database of regional redlists that includes values for scientificName and statusCode (to record a taxon with its respective threatened status). We have values like LC (least concern) and EN (endangered), as well as NA (not applicable).
Would storing the value NA (as a string) be a problem in the future? e.g., for users reading the data.
Should we use an alternative, e.g., lowercase values, to record these statuses?
Do you have experience with NA values being problematic (as they can be confused with NULL or empty values)?
My opinion is to keep the uppercase values since they are well-known, and to just warn users.
Any general suggestions/recommendations would be very much appreciated.
Thanks a lot!
Best,
Flo
@flograttarola, it’s good that you asked for opinions, since there are no absolute rules!
For your conservation concern field, the IUCN recommends “DD” (Data Deficient) if data are very uncertain (https://portals.iucn.org/library/sites/library/files/documents/RL-2001-001-2nd.pdf):
“However, in this case the assessor must provide documentation showing that this category has been assigned because data are inadequate to determine a threat category. It is important to recognize that taxa that are poorly known can often be assigned a threat category on the basis of background information concerning the deterioration of their habitat and/or other causal factors; therefore the liberal use of ‘Data Deficient’ is discouraged.”
If the taxon has not been investigated for conservation purposes, the IUCN suggests “NE” (Not Evaluated).
More generally, if information is not available to fill in a field, a common recommendation is to leave the field blank:
“The null value that is most compatible with the software commonly used by biologists is the blank (i.e., nothing)” ( Nine simple ways to make it easier to (re)use your data | Ideas in Ecology and Evolution )
Data Organization in Spreadsheets for Ecologists: Formatting problems Best option is blank for null values
Blank is also the entry I personally recommend for no-data Darwin Core fields: Darwin Core checker: Within fields . You can always explain the blank in a Darwin Core “…Remarks” field if necessary.
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Thank you so much for such a detailed reply, @datafixer!
I read, liked, and fully agree with your entry on using blanks for Darwin Core fields.
I should have mentioned that “NA” is a category for the regional redlists (in addition to the global ones, such as RE: regionally extinct). The definition is “Not Applicable (NA): Category for a taxon deemed to be ineligible for assessment at a regional level” (https://portals.iucn.org/library/sites/library/files/documents/RL-2012-002.pdf). So we have values that are effectively “NA” and not blanks.
@flograttarola , many thanks, I had never seen the “NA” category for regional redlists. It’s an unfortunate abbreviation, because it means one thing in this particular context and something else in other contexts. The IUCN goes on to say “In contrast to other Red List Categories, it is not
mandatory to use NA for all taxa to which it applies; but is recommended for taxa where
its use is informative”, without explaining how “informative” should be communicated. I’m guessing you will have at least one field in your database with explanations for assignments to categories, so “NA” + explanation would be sensible. Using the regional-redlist “NA” in other databases would be ambiguous without that other, explanatory field.
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