I just so happened to glance through the book Plain English, Collinson, D. (1995). Buckingham: Open University Press. I noticed that the word ‘Data’ is actually a plural rather than a singular.
The following sentence is actually, grammatically incorrect.
Data that is more than five years old is of limited use
And should be:
Data that are more than five years old are of limited use
After doing some googling (as I actually couldn’t work out why this was wrong initially) I discovered that Datum should be used as the singular. Having worked in IT for over 10 years, if I said the word “Datum” to anyone they’d look at me and laugh! In technical writing the answer is to consult the style guide. It also appears that most articles use data as a singular and it’s authors choice. I personally think that this term should be updated!