The phrase "some subset" is correct and usable in written English.
You can use it when referring to a subset of a larger set, such as "some subset of the data was larger than the rest".
Arming some subset of the rebels does not necessarily buy us influence.
"We think this could facilitate communication with at least some subset of these patients," he says.
Perhaps some subset of this group is more expert than the others?
So profit is some subset of this, but it's not all of this, okay.
Some subset will have an A there, and a T there.
First, the venture capitalist may have superior information with respect to some subset of employee innovations.
So profit is some subset of this but not the totality of it.
The Liberal Democrats are not just some subset of the Labour or Tory parties – we're no one's little brother.
Several detectors exist that will be capable of observing some subset of those neutrinos.
A map task applies the map function to some subset of the input data and outputs intermediate key-value pairs.
You were just talking a little about it -- namely, that some subset of your rich countries are very decentralized.
