Data is typically not a plural10 June 09. [link] PDF version
When we learned all those darn grammatical exceptions, we were usually told that they came about in some distant past, due to some arcane relic of old Dutch or something. But here in the new millennium, we have the chance to witness the development of a new grammatical exception.
If this sounds boring, bear with me: by the end of the column, about 360,000 people will die over this corner of grammar.
English has the concept of a collective singular, wherein a group of elements is treated as a unit: e.g., that clump of birds is moving pretty fast. The new exception is that this concept can apply to any group of anything except data. For example, the data shows a steep slope is considered incorrect by some, who prefer the data show a steep slope.
If you are one of the people who think that the data is is always wrong, please stop.
Let us imagine a world where English grammar would require all groups to remain plural:
1. The agenda are on the table.
2. The trivia in this book are silly.
3. Steely Dan are playing at the pavillion.
4. Boris Godunov are a wonderful opera.
5. The NIH owe me \$12,000.
6. The U.S.A. are in a recession.
1. Agendum/agenda has the same Latin-based form as datum/data. Yet I have never heard a person who uses the data are use the agenda are.
2. Sentence #2 is the only one that is actually incorrect, due to the odd history of trivia. Here's the definition of trivium from the OED: “in the Middle Ages, the lower division of the seven liberal arts, comprising grammar, rhetoric, and logic.'' That is, trivium was itself once a collective singular. The meaning evolved, and we can now group together a collective unit of facts about the trivium into bundles that are collectively a unit: trivia. In the present day, trivia is always a singular, because trivium refers not to individual facts but to the above fields of study. The singular of trivia is basically lost. And since I know you're gnawing to know, the other part of the seven liberal arts is the quadrivium: “the four mathematical sciences, arithmetic, geometry, astronomy, and music''.
3. Bands and orchestras are a great example of the whole being more than its parts.
4. The singular of the Latin for a work is opus; an opera comprises a collection of works.
5. The acronym in number 4 expands to National Institutes of Health, and they do continue to “lose'' my invoices as quickly as I can send them. Acronyms are a great way to cohere a plural into a singular.
6. The 360,000 casualties mentioned above come from #5: the question of whether the U.S.A. are or the U.S.A. is is the difference between a Confederacy and a Federation, and was basically resolved by a civil war. People fought and died over the question of whether a set of elements should be taken as separate elements or a unit, just a box of parts or a coherent whole.
We use the collective singular when the collective is more than the sum of its parts. Spaghetti is a dish that has little in common with eating one spaghetto at a time. As such, the data is implies that we can learn something from the data as a whole that we don't learn by looking at one line at a time, while the data are implies that there is no added value to aggregating a list of points to form a whole, and thus embodies a profoundly pessimistic view that Statistics are not worth studying.
More mundane examples still reveal different points of view. Both the flock of birds are flying and the flock of birds is flying are correct, but one or the other probably sounds off to you. Maybe you flinched when I wrote agendum/agenda has at bullet point one above. Here, grammar is a window to the soul. I think that some people generally lean toward seeing the parts and some generally lean toward seeing the whole. Linguist readers are welcome to leave citations regarding my claim in the comments. In one case this difference in thinking led to a war, but in most cases it seems to just lead to people correcting other folks' grammar when the grammar really just reflects a difference in perception.
Oh, and hair is an interesting case: there's a form your hairs for a set of items that is not to be taken as a whole, and your hair referring to the whole mop on your head. It'd be great if we'd evolved more pairs like that, like maybe datums and data.
The math section
Let's get back to data, which is in the mathematical realm. Precision matters in math, and grammar needs to follow along. The sentence that set of numbers is prime is incoherent: only the individual numbers can be prime; a set can't be prime. The sentence that set of numbers are dense is incoherent: only the set as a whole can be dense; individual numbers are not dense. We thus need both the set of numbers is and the set of numbers are in our grammar.
Similarly with data: sometimes we are looking at the gestalt, such as a statistic like the estimates of a regression parameter or whether the line implied by the collective slopes upwards; sometimes we are looking at the individual elements, such as when we point out that all the numbers are positive. The data are a matrix is anacoluthon: on the left-hand side of the are, we refer to a plural, while on the right-hand side, we have a singular; the sentence reduces to a plural = a singular. It's a perfect demonstration that the left-hand side is meant to be taken as a collective singular, as expressed perfectly by the data is a matrix.
So, a simple rule for authors:
- If by the data you mean the data points, then data is a plural noun.
- If by the data you mean the data set, then data is a singluar noun.
As a reader, that means that the grammar gives you one more clue as to the author's intent. Good grammar is wonderful that way.
Why the new exception?
So why are we OK with the agenda is and the set of elements is, while the data is is now considered to be wrong? None of the reasons I can think of are very positive.
Fowler's Modern English usage (2nd ed., 1965) calls these “nouns of multitiude'' (see the entry on number, part 6), and explains that “They are treated as singular or plural at discretion—and sometimes, naturally, without discretion.'' I expect that many of the people who have learned to use the data are learned the rule so that they don't have to agonize at every sentence about which to use, which is one of the key points of having grammatical rules to begin with. For what it's worth, Fowler on data: “Latin plurals sometimes become singular English words (e.g. agenda, stamina) and data is often so treated in U.S.; in Britain this is still considered a solecism, though it may occasionally appear.'' [sub-digression: the English singular corresponding to stamina is stamen.]
This is a subjective perception, but I've seen bullying on the part of people who insist that data be plural, even more than on other grammatical issues. E.g., one discussant at a conference session I attended devoted a slide to chiding an author over the use of the data is. Given how many academic authors are non-native English speakers forced to write and speak English, I think extended grammatical nitpicking easily borders on intolerance. Srsly, unless your job is copyediting, stick to the substance.
To be even more negative, I get the vibe that the people who correct the data is are just trying to indicate smartness—and failing. The process is perfect for the person working too hard at smart: (1) Identify trivia: data is actually a plural, and has a Latin-sounding singular. (2) Payoff: feel smarter for knowing trivia. (3) Find somebody who seems to not know the fact. (4) Big payoff: correct them!
Another of my pet peeves fits the same form: the use of methodology (the study of methods) as a synonym for method. Look at me! I used a five-syllable word! I think it's a synonym for a two syllable word, but I chose to use the longer word anyway!
But, as above, there are times when data is a pile of parts, and times when it has meaning only as a whole. In all sorts of situations, our brains are wired to sometimes see the parts and sometimes the whole, and there's no point starting wars with people who see things differently.