Is "Data" Singular or Plural?

The data are correct or The data is correct? 

Answered from Charles Carson, managing editor of the journal American Speech

The question seems easy enough: is data singular or plural? Unfortunately, the answer is that both usages are standard.
We could explain why grocery store signs should read 10 items or fewer instead of 10 items or less. Count nouns are used for objects that can be counted; that is, they're distinct objects that can be numbered. For example, in my refrigerator there are eggs, apples, and lemons. These are all count nouns. Count nouns can be singular or plural, and when you use them as the subject of a sentence, the verb must correctly reflect that number, as in

The last apple IS on the bottom shelf

or

The eggs ARE fresh.

Mass nouns, on the other hand, are used for things that don't have a natural boundary and can't be counted. Also in my fridge are butter, iced tea, and bacon. These are all mass nouns. Mass nouns always take a singular verb, as in:

 The iced tea IS already sweetened and They say bacon IS bad for you, but I love it.

How Many or How Much?

An easy way to tell these two types of nouns apart is to ask yourself how many or how much. If it makes sense to ask how many there are of a noun, as in how many cars or how many people, then it's a count noun. If, however, it makes more sense to ask how much there is of a noun, as in how much butter or how much rain, then it's a mass noun.

The use of many and much parallels the use of fewer and less: many and fewer are used with count nouns (like items in a grocery cart) and much and less are used with mass nouns, like tea or bacon.

How Many Data or How Much Data?

Now let's get back to our original question, is data singular or plural? Or, more accurately, is data a mass noun — remember, a mass noun always takes a singular verb — or is data a count noun,the plural of datum.
As I said, both usages are standard. The count noun datum and its plural data, meaning "a given fact or assumption," were adopted from Latin into English by the seventeenth century ; however, it wasn't till the late nineteenth century that data took on the modern sense of facts and figures. This shift in meaning also led some to start treating data as a mass noun.
So if data is correct as both a count noun and as a mass noun, which should you use? It comes down to style and personal preference. Many academic and scientific fields, as well as many publishers and newspapers, still insist on the plural count noun use of data, as in The data are compelling, but it is more commonly used as a singular mass noun, as in The data is compelling.
If you write for an organization or discipline that insists on the plural count noun usage, pay attention to other words in the sentence that are sensitive to number. For example, an author might write the following sentence:

Much of this data is useless because of its lack of specifics.

If the publisher allows for the singular mass noun usage, that is an acceptable sentence. If, however, the publisher insists on the plural count noun usage, an author might change the verb is to are, making the sentence read as follows:

Much of this data are useless because of its lack of specifics.

That change, however, makes the sentence ungrammatical. Note that the author wrote MUCH of THIS data. Count nouns answer how many, not how much. It should be changed to MANY of THESE data. The sentence also reads because of ITS lack of specifics; the author here should use the plural pronoun their,because of THEIR lack of specifics. Thus, the correct sentence should be as follows:

Many of these data are useless because of their lack of specifics.

If that sounds odd to you, as it does to me, then you probably use data as a mass noun and would treat data as singular — and there's nothing wrong with that. Just be aware that if you do write or edit for a publisher or in a discipline that insists on plural data, you should make sure the surrounding words properly reflect the plural treatment of the word data. Even if you don't have a style guide insisting on the plural usage but you decide to use it anyway because you like Latin plurals, be sure to do it consistently throughout the document — in other words, don't mix up your datas, using it as a count noun in one place and as a mass noun in another.

A Quick and Dirty Way to Check Your Writing

Here's a quick and dirty tip to check your own use of data. 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.


Notes
Whenever I talk about mass nouns, I often hear, "Oh, you mean like fish." Well, yes and no. Fish is a tricky example. It can be used as a mass noun in the general sense noted above (as in Fish is good for you), but it's a better example of nonstandard plurals (what linguists call the zero-plural marker): fish is used for both the singular count noun and the plural count noun (one fish, two fish, as Dr. Suess wrote).

Nouns frequently cross the line between mass and count. For example, count nouns can be used as mass nouns if one intends a more general sense, as inThere's too much lemon in my tea. Here lemon, usually a count noun, is used in a more general sense. In the other direction, mass nouns can be used as count nouns if the speaker is referring to established amounts. For example, in That table needs three waters, the word water, usually a mass noun, is used to indicate the three usual amounts of water -- in this case, glasses of water. Mass nouns can also be used as count nouns to indicate a variety of types. For example, wine and cheese are mass nouns, but one can speak of different types of wines and cheeses.

‡It should be noted that some usage scholars, while acknowledging that data can be used as a plural, do not view data as a true plural count noun (1). This is because plural data fails the number test. A distinguishing feature of count nouns is that they can be modified by a cardinal number (one, two, three, etc.), as in one chair, two mountains, three bottles, etc. Data, on the other hand, cannot be used after a cardinal number (two data is not grammatical). Despite this debate, however, all agree that plural data, whether a count noun or not, still requires the same plural agreements (are, these, many, etc.).
The singular count noun datum is not as common as data, but it is used frequently in academic, scientific, and technical writing. Listener Gabriel from Los Angeles left a voicemail asking about data and warned that before we declare datum dead, we should know that he encounters it frequently in his work in fluid mechanics and with topographical maps. In some disciplines, like geodesy, the plural datums is used instead of data. Other fields completely avoid the singular/plural data question by combining data with other words to make them unquestionably count nouns, as in data point or data set.
It is not uncommon for nouns to change from count nouns to mass nouns or vice versa when borrowed into another language, as is the case of information, which is mass in English, but countable in the language English borrowed it from, French (des informations), and in the original Latin (information-em). (2). According to David Crystal, "There is no logical reason why nouns should be count or mass: a concept may be countable in one language, but mass in another" (3).

Posted in: Grammar