  We examine the effect of a threshold bias on the power spectrum and the
bispectrum in an ensemble of numerical simulations (Gaussian initial
perturbations with power law spectra P(k) \sim k^n, n=+1, 0, -1, -2) and
compare our results with theoretical predictions. Our simulations are evolved
sufficiently that on the scale where we apply the threshold the rms fluctuation
has developed significantly into the nonlinear regime. Thus, predictions based
on perturbation theory do not necessarily apply. Nevertheless, we find our
results for the power spectrum, biased power simply amplified by a numerical
factor, follow predicted trends, far beyond the regime where perturbation
theory is expected to be valid. We find that the biased bispectrum continues to
follow the so-called hierarchical form, with reduced three-point amplitude Q
\approx 1 in the strongly nonlinear regime, independent of initial spectrum. In
the quasi-linear perturbative regime the three-point amplitude depends on
configuration shape, a behavior that is found to give useful information about
the amount of bias without information about the unbiased matter distribution.
