The phrase "a relatively small pool" is correct and usable in written English.
It can be used when referring to a limited or restricted group of options, resources, or individuals in a particular context.
Example: "In our study, we focused on a relatively small pool of participants to ensure more in-depth analysis."
Alternatives: "a limited selection" or "a modest group".
Only a relatively small pool of money can be used in advertising that is coordinated between the party and the campaign.
But Ms. Palmer's ability to raise such a great sum from a relatively small pool of dedicated fans has drawn the attention of the music industry.
If you're limiting yourself to people who've passed exams or can afford the cost of private university fees you limit yourself to a relatively small pool".
Republican officials insist that their financial base is primarily small donors, but the party has received more than $90 million from a relatively small pool of wealthy individuals and corporations, some of whom have shielded their generosity from public view.
As they point out, this leaves a relatively small pool of loopholes to close – big enough that the Romney tax cuts could, in principle, be paid for by base broadening, but not with a lot of room to spare.
Department officials said that when they began placing officers at bridges, tunnels and other important security posts around the city -- assignments that typically require greater firepower than those given to most of the rank and file -- they were forced to choose from a relatively small pool of officers trained in the use of heavy-duty weapons.
The company's easy-to-use, drag-and-drop interface makes the once-intimidating exercise of editing video footage accessible to an audience far larger than the relatively small pool of tech-savvy video enthusiasts who have editing software on their PCs.
Mrs. Clinton, of New York, and Mr. Obama, of Illinois, are betting that they can use computer-driven research to expand the relatively small pool of caucusgoers.
(There is also the muddle of how to deal with motion-capture animation and the relatively small pool of qualifying films – only 18 this year).
But given the relatively small pool of prize money and busy training schedules, some runners may run in only one meet.
More disturbing, said Mr. Shulman, was that about 20 percent of people on the RockYou list picked from the same, relatively small pool of 5,000 passwords.
