"Data" is the Latin plural of "datum," so why does it sometimes sound weird when people say "the data are" instead of "the data is"?
Oxford Dictionaries maintains that “data" has developed two separate meanings:
- the original plural meaning that conveys the idea of multiple data bits or pieces
- a singular meaning that acts as a mass noun roughly equivalent to the word “information.”
Dictionaries and news sites including the Wall Street Journal and The Guardian, and style guides including The Chicago Manual of Style have updated their recommendations to allow that “data” can be singular or plural.
However, science and medicine are two areas where treating “data” as plural has held on tighter than in other areas. For example, APA style (the style of the American Psychological Association) specifies that “data” is plural, as do the guidelines for the Journal of the American Medical Association.
Garner’s Modern English Usage actually calls “data” a skunked term, meaning you can’t win—whether you treat it as singular or plural, someone will think you’re wrong.
One solution is to try to write around the problem, for example, by using the terms “data point” or “information.”
After that computer back-up, “Your information is now safe,” would be an equally satisfying completion message that also wouldn’t annoy people who think “data” should be plural.
‘Much Data’ or ‘Many Data’?
Another important point to consider is when to use “much” and when to use “many.” If you’re treating “data” as a mass noun, singular, use “much.”
Much data suggests that snails are drawn to chocolate.
Just as you’d say, “Much poetry is underappreciated,” or “Much of my favorite art is in the Museum of Modern Art in New York.”
If you’re treating “data” as the plural of “datum,” use “many.”
Many data suggest that snails are drawn to chocolate.
Just as you’d say, “Many poems are about love or loss,” or “Many of my favorite paintings are at the MOMA.”
The Bottom Line
The bottom line is that in general writing, you’re free to use “data” as singular or plural depending on what sounds right to you, but know that if you treat it as singular, some people might complain. If you want to use a singular noun, it’s safer to use a synonym such as “information” or “evidence”; and if you’re writing about science or medicine, definitely treat “data” as plural.
[Update: 2-6-2018: Another example of words such as "data" and "agenda" is "podia," the plural of "podium."]
Examples: ‘Data Is’ and ‘Data Are’
Remember the cell phone that was never used? Well, it was used. Only all the data was hard-erased. [“Data” isn’t wrong, but “information” would be a safer choice.]
— Pauley Perrette playing Abby Sciuto in the TV show “NCIS"
Few weather stations dot remote and high-altitude locales and where they do exist their data are often incomplete.
—Brian Handwerk writing for “National Geographic"
Mignon Fogarty is Grammar Girl and the founder of Quick and Dirty Tips. Check out her New York Times best-seller, “Grammar Girl’s Quick and Dirty Tips for Better Writing.”