"DATA ARE valuable".
Is 'data' like water or like sheep? :) Can whatever-it-is be counted (like sheep) or not (like water). Eg:
Water are valuable. (Wrong!!)
Sheep are valuable. (Perfectly acceptable, phew!)
For me, data is like water.
'Data is valuable'.
'A piece of data is valuable'.
'Lots of pieces are valuable'.
'Data are valuable' <- sounds all wrong!
Usage as a plural noun is an Economist house style choice[2].
It's hard to tell how well the Economist sticks to that style choice. A Google site: search, with a date range of the last 10 years, shows no usage of "datum" (except for the article about the subject).
An Google site: search for usages of "data is" in the last 10 years returns plenty of results.
[1] https://trends.google.com/trends/explore?date=all&geo=GB&q=%... [2] https://www.economist.com/graphic-detail/2012/07/13/data-or-...
If this was ever a debate, it was decided a long time ago. Grammarians may choose to argue the point (as if our language was defined in Ancient Rome) but saying "data are" sounds like simple-minded country bumpkins struggling to come to grips with it all.
Nit: "Is" is singular because of "piece," not "data." As in, "the pieces of data are valuable."
They are referring to a data file.
Sometimes they say “we need more data” and they really mean more data points.
I rarely hear the term “datum” but it’s not technically incorrect, just a bit out of touch.
What is a datum? Any piece of data will have multiple properties, so a singular piece is really a data point, which implies a number of bits of datum. I know it’s hard to understand this stuff.