The word data is almost universally used as a singular mass noun in English except among many professional writers and academics who insist that it is the plural of datum, a word that is almost non-existent in English outside discussions of whether data is a plural. The reason usually cited for treating data as a plural is that it was a plural in Latin, which is true but irrelevant since grammatical changes often occur when words are borrowed from one language to another. A perfectly analogous example is the word spaghetti which is a plural count noun in Italian but very clearly a mass noun in English, which is why native speakers of English say This spaghetti is cooked and not These spaghetti are cooked.
