  In a companion paper we presented a statistical model for the blazar
population, consisting of distributions for the unbeamed radio luminosity
function and the Lorentz factor distribution of each of the BL Lac and Flat
Spectrum Radio Quasar (FSRQ) classes. Our model has been optimized so that it
reproduces the MOJAVE distributions of apparent speeds and redshifts when the
appropriate flux limit is applied and a uniform distribution of jet viewing
angles is assumed for the population. Here we use this model to predict the
Doppler factor distribution for various flux-limited samples for which Doppler
factors have been estimated in a variety of ways (equipartition, variability +
equipartition, inverse Compton dominance) on a blazar-by-blazar basis. By
comparing the simulated and data-estimated Doppler factor distributions in each
case, we evaluate the different methods of estimating blazar Doppler factors.
We find that the variability Doppler factors assuming equipartition are the
ones in the best agreement with our statistical model, whereas the inverse
Compton Doppler factor method is only suitable for FSRQs. In the case of
variability Doppler factors, we find that while random errors are relatively
low ($\sim 30\%$), uncertainties are dominated by systematic effects. In the
case of inverse Compton Doppler factors, random errors appear to dominate, but
are significantly larger ($\sim 60\%$).
