An experimentally determined diffusion coefficient is related to the amplitude of a continuum spectrum of drift‐wave‐like fluctuations. It is found that the diffusion coefficient depends upon the amplitude of the fluctuation in a way which is consistent with the nonlinear diffusion theory of Dupree; that is,D⊥ ∼ ⟨&dgr;n2⟩for small amplitude and∼ ⟨&dgr;n2⟩1/2for large amplitude. An elementary model which predicts the relative fluctuation amplitude⟨&dgr;n2⟩/n02and the autocorrelation time of the continuum spectrum of driftlike waves is also presented and shown to be in agreement with both the properties of the observed spectrum and the results of the diffusion measurements.