We consider the Wigner quasi-probability distribution function of a single mode of an electromagnetic or matter-wave field to address the question of whether a direct stochastic sampling and binning of the absolute square of the complex field amplitude can yield a distribution functionPn that closely approximates the true particle number probability distribution Pn of the underlying quantum state. By providing an operational definition of the binned distributionPn in terms of the Wigner function, we explicitly calculate the overlap betweeñ Pn and Pn and hence quantify the statistical distance between the two distributions. We find that there is indeed a close quantitative correspondence betweenPn and Pn for a wide range of quantum states that have smooth and broad Wigner function relative to the scale of oscillations of the Wigner function for the relevant Fock state. However, we also find counterexamples, including states with high mode occupation, for whichPn does not closely approximate Pn.