If you’re a grammar grinch, you probably suffered a slight heart attack upon reading that title. It’s a grammar problem that plagues researchers to no end. In fact, it’s a problem that really isn’t a problem as I learned recently.
Below you’ll find the rule as well as a link to the original source with nine other rules you’ve been getting wrong all along. Enjoy!
8. Treating “data” as singular instead of plural: Remember what I said about Latin screwing with your life? “Data” is a word that makes lots of people unhappy. It comes from the Latin word “datum,” a second declension neuter noun that becomes “data” in the nominative and accusative plural. (Latin has different plurals for different parts of speech.) We’ve inherited a lot of Latin plurals, and many of them we no longer treat as plural: for example, we say “the agenda is” rather than “the agendas are” and “opera” is not the plural of “opus” in English.
In some cases, using “data” as plural is legitimately useful. You’re more likely to encounter “data” as plural in scientific and mathematical writing where you might talk about collecting each individual datum. My 2007 copy of the AP Stylebook uses “The data have been collected,” as an example of a sentence where “data” is being treated as a group of individual items. In that case, “data” is being treated as what we call a “count noun.”
While some style guides will recommend always using data as plural, in daily speech we frequently use data as what’s called a “mass noun,” meaning it has no natural boundary, no individual units that we can count. Charles Carson, managing editor of the journal American Speech, uses “butter” as an example of a mass noun. Sure, you can talk about pats of butter or cups of butter, but when you talk about just butter, you say, “How much butter is in the pie crust?” When using data as a mass noun, it is perfectly standard English to treat it as grammatically singular.
Carson employs this handy rule of thumb:
If you wish to use data as a singular mass noun, you should be able to replace it in the sentence with the word information, which is also a mass noun. For example,
Much of this information is useless because of its lack of specifics.
If, however, you want to or need to use data as a plural count noun, you should be able to replace it with the word facts, which is also a plural count noun. For example,
Many of these facts are useless because of their lack of specifics.
O’Conner deems treating data as a grammatical plural a dead rule, writing, “No plural form is necessary, and the old singular, datum, can be left to the Romans.” She also argues that media should be treated as singular when referring to mass communication and as plural only when referring to individual types of communication.