September 11, 2014

Weekly Language Usage Tips: data is or data are

Posted in data is or are at 6:01 am by dlseltzer

Tip: Data—plural or singular

A reader writes:

I am confused. I read several different scientific journals, and I am stymied by the different ways that the word, data, is used. Sometimes, it’s ‘data is,’ and sometimes, it’s ‘data are,’ and I don’t know which is correct? Could you tell me what the story is with respect to ‘data’? Thanks for your input.

This is an oldie, but a goodie. Whether the word, data, is singular or plural has been a bone of contention for what seems like eons. It’s certainly been the object of dispute since before most of WLUT’s readers were born. Heck, it has been debated since even before I was born. Eons, I tell you.

On one hand, the answer is simple: the word is plural in form and, thus, takes a plural noun:

The data are unequivocal; they show that our primary hypothesis is correct.

On the other hand, the answer is complicated: the word, data, is commonly used as a singular mass noun:

The data is as clear as it can be: your hypothesis is wrong.

And this usage (the singular data) has become widely accepted in all but the most formal scientific writing. The question of right and wrong becomes difficult to address—it’s more of a question of usage, it seems to me.

So what do I recommend? First of all, consistency is essential when it comes to matters of writing and grammar. If you use data as plural in one sentence, it should be used as plural throughout the manuscript. It can’t be plural here and singular, there. (Lack of consistency is one of the most common mistakes I find when reviewing scientific documents, and I have to say, it makes me a little crazy, so cut it out!)

Second, when writing scientific papers, stick to the old school, in which datum is singular and data is plural (I’m referring to the word not to what it represents so that’s why the ‘is’ is used there—does that make sense? If not, let me know, and I’ll try to explain further). Most medical and scientific journals still abide by the traditional usage, and no one will look askance at that.

Third, in casual writing, it is really writer’s choice. It is not considered wrong these days to use data as a singular mass noun. But just be consistent in how you use it within a single document.

So I haven’t really answered the reader’s question—which is right and which is wrong—I’ll just say that they are both right, but in some contexts, like scientific writing, the plural form is more accepted.

I hope that helps.


  1. Anonymous said,

    May I please receive this post as an email?

    • dlseltzer said,

      done. welcome.

  2. L.E. Ohman said,

    I love this stuff. Please add me to your email list

    • dlseltzer said,

      Will do.

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