While present experiments are evaluated on the basis of confinement time, it is the fusion power multiplication factor, Q, and the fusion power that will be the parameters measuring the performance of ignition experiments and fusion reactors. We have determined the relationship of Q to τE and the Lawson number, nτE, for ohmically heated plasmas from the Princeton large tokamak (PLT). The values Q, τE, and nτE all increase with density at low densities. Above e ≃ 4 × 1013 cm−3, τEe ≃ 30 ms, or eτEe ≃ 1.2 × 1012 cm−3s, Q saturates; Q scaling has also been obtained on PLT as a function of toroidal magnetic field, plasma current, and auxiliary heating power.