Although I'm not positive of it and I admit I may be wrong, I think operations research had a role in designing our personnel system, in terms of input-throughput-output. At the entrance to the personnel pipeline there are accessions, which in turn feed the scoolhouses, and after that TOE units. Throw in all the mid-career schools for different specialties and so forth, then the planning gets complicated. The system works after a fashion, but it treats everyone of the same MOS and grade as though they're interchangeable and it doesn't always put the best qualified people in the best slots. Training is another ball of wax, but that's TRADOC, not personnel.