When speaking explicitly about any type of set, a given set is also defined as a ” Subset ” of itself.

If you want to precisely describe a partial dataset, you would instead refer to a “Proper Subset ” — so perhaps one would say you’ll be ” selecting and/or extracting (proper) subsets from the entire dataset. If

you can’t explicitly point out the non-entirety of it for an argument, omitting the “proper” should be your rule.