“These data are …” or “This data is …”?
Singular or plural?
Definition of “data”: factual information, as measurements or statistics, used as a basis for reasoning, discussion, or calculation (Merriam-Webster Dictionary).
Pronunciation: [deɪtə], [dætə], or [dɑːtə]
Especially in writing, the question arises whether to treat "data" as a plural noun or as an uncountable mass noun (just like e.g. “information”, “money”, and “research”). Should one write: “These data are ...”? Or instead: “This data is …”?
In theory, and consistent with the rules of Latin grammar and traditional English, data is a plural noun (e.g. “These data are confusing”). However, data is today commonly treated as an uncountable mass noun, particularly in everyday usage (e.g. “This data is confusing”).
Although both versions are correct, take into account that even native English speakers might not know this. In a spoken context, such as a presentation, it is therefore advisable to use data as an uncountable noun (“This data is …”), in scientific texts one should rather prefer the use of data as a plural.