СФ
> The Associated Press style guide classifies data as a collective noun that takes the singular when treated as a unit but the plural when referring to individual items (e.g., "The data is sound" and "The data have been carefully collected").
а Chicago Manual of Style говорит вот что:
> data. Though originally this word was a plural of datum, it is now commonly treated as a mass noun and coupled with a singular verb. In formal writing (and always in the sciences), use data as a plural.