People will argue about this one.
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.
Thanks, Adam, for your request. I hope that helped.
Thanks to Charles Carson, managing editor of the journal American Speech, for guest-writing this episode; and thanks, Adam, for your question.
*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 in There'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).
1. Merriam-Webster's Dictionary Of English Usage. Springfield, MA: Merriam-Webster, 1989.
2. Oxford English Dictionary. Second edition. 12 vols. Oxford: Clarendon.
3. Crystal, D. A Dictionary Of Linguistics And Phonetics. Fifth edition. Malden, MA: Blackwell, 2003.
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