Create date quality categories

[peterdesmet]

Description

For a given dataset, I want to know how many records have dates. I also want to know how many of those are useful, have issues, and maybe what their precision is. I envision this as a bar chart, where the records are grouped in categories based on the quality of the dates.

Categories (in order of increasing data quality)

• Date not provided
• Date with major issues
• Date with minor issues
• Valuable date (all in ISO8601)

  Questions

• [ ] GBIF sets many dates to blank without trowing an issue (see #27).
• [ ] GBIF makes no attempt at signaling dubious dates: in fact, it throws RECORDED_DATE_MISMATCH if day, year, month are correctly provided.
• [ ] RECORDED_DATE_UNLIKELY also matches invalid dates: 99 XXX 9999
• [ ] So the 3 relevant issues RECORDED_DATE_INVALID, RECORDED_DATE_MISMATCH and RECORDED_DATE_MISMATCH are of limited use to indicate the data quality. One approach to provide much more relevant date information, is to use the Canadensys Narwhal Processor.
• [ ] If no eventDate is provided, GBIF doesn't seem to look in verbatimEventDate or year, month, day. The literal values of those fields are shown on the website though.

  Terms we need

eventDate
issue
eventDate from verbatim.txt
verbatimEventDate
year
month
day

Process

IF eventDate != "" AND issue DOES NOT CONTAIN (
        RECORDED_DATE_MISMATCH
    )
    THEN category = "Valuable date (all in ISO8601)" /* Well, MM-DD-YYYY are still in there */
ELSEIF issue CONTAINS (
        RECORDED_DATE_MISMATCH /* The only issue that keep eventDate populated */
        )
        verbatim.txt.eventDate != "" /* Since GBIF empties eventDate (see #27) in occurrence.txt, 
            we'd have to look in verbatim.txt :( */
        OR verbatimEventDate != ""
        OR year != ""
        OR (year != "" AND month != "")
        OR (year != "" AND month != "" AND day !="")
    /* A date was provided */
    THEN category = "Date provided, but not interpreted by GBIF"
ELSE
    category = "Date not provided"

[peterdesmet]

The pretty useless process if we just use GBIF issues:

IF issue CONTAINS (
        RECORDED_DATE_INVALID
        RECORDED_DATE_MISMATCH
        RECORDED_DATE_UNLIKELY
    )
   THEN category="Date with issues"
ELSEIF eventDate != ""
   THEN category="Valuable date (all in ISO8601)"
ELSE
   THEN category="Date not provided" /* This is just incorrect! See issue #27 */

[peterdesmet]

@bartaelterman, @niconoe, I need your feedback on this issue:

1. We need to look in verbatim.txt to get a useful eventDate (as GBIF overwrites them without warning in occurrence.txt, see #27 - need to confirm with them that no field in occurrence.txt has the original eventDate). If so, how challenging is it to loop over that file too?
2. Do we use the Canadensys Narwhal processor to provide high quality categories, instead of the current basic ones?
3. Or do we not tackle this issue in this POC?