In most writing data will be treated as a singular noun:
- “This data shows how people use language" (rather than "these data show”).
- "The data is clear and convincing” (rather than “these data are clear and convincing”).
In these examples data is a noncount noun, like information (meaning it refers to something that cannot be counted). In this type of use it is treated like a singular noun even when if refers to multiple pieces of data (“Participants’ data is not kept after the survey ends.”)
In technical or scientific contexts (and in some formal writing) data will be treated as a plural noun:
- “These data show how people use language” (rather than “this data shows”).
- "These data are clear and convincing” (rather than “the data is clear”).
In these examples data is a count noun (meaning it refers to something that can be counted), like graph. In this type of use it is treated as the plural form of datum (“a single piece of information”).
When data is used with computer science or digital technology it usually is treated as a singular noun, even if the context seems rather technical.
- “We encrypt our data so that it cannot be read by other users.”
- “Students’ computer data is kept private.”
