05 March 2016
The word "data" has some controversy surrounding it. The controversial aspect is not its origin. In English, it is a mid 18th century word from Latin datum, meaning literally "something given,’" (neuter past participle of dare ‘meaning "give." "Data" is the Latin plural of "datum", and still may be used as a plural noun in this sense, but today "data" is most commonly used in the singular, as a mass noun, in the way that we use "information", "sand" or "rain."
There is some controversy on its pronunciation. Some people say day-tah and some sat dah-tah. But there is also disagreement about its usage.
Data is facts and statistics collected together for reference or analysis. But is data a singular, uncountable noun, or should it be treated as the plural of the now-rarely-used datum?
In most cases, even if the quantity of data is singular (one number, for example) we say "data" as opposed to datum.
Though I don't think I have ever used the word, "datum" is apparently used in some fields to mean "an item given". I found that "In cartography, geography, nuclear magnetic resonance and technical drawing it is often used to refer to a single specific reference datum from which distances to all other data are measured. Any measurement or result is a datum, though data point is now far more common."
The New York Times use "data" either in the singular or plural: "the survey data are still being analyzed" and "the first year for which data is available." The Associated Press style guide classifies data as a collective noun that takes the singular when treated as a unit but the plural when referring to individual items ("The data is sound.", and "The data have been carefully collected.").