Results of Monte Carlo simulations to derive the jet Lorentz factor Γ and the intrinsic spread of core dominance σ_intr. The left panel shows the core dominance difference, Δlog R, of a simulated sample of HIGs and BLOs as a function of Γ. The black solid curve is for the average value, while the green line is for the median. The horizontal lines show the observed values, with the dashed lines representing the errors. Right panel: curves of the intrinsic spread of core dominance, σ_intr, required to reproduced the observed values of the widths of the core dominance distributions for HIGs (black) and BLOs (red) as a function of Γ. At the intercept the constraints for HIGs and BLOs are simultaneously satisfied. The dashed lines for each class are obtained by considering the errors on the dispersions.