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...