We describe quantum-field-theoretical (QFT) techniques for mapping quantum
problems onto c-number stochastic problems. This approach yields results which
are identical to phase-space techniques [C.W. Gardiner, {\em Quantum Noise}
(1991)] when the latter result in a Fokker-Planck equation for a corresponding
pseudo-probability distribution. If phase-space techniques do not result in a
Fokker-Planck equation and hence fail to produce a stochastic representation,
the QFT techniques nevertheless yield stochastic difference equations in
discretised time
