6.7 GHz methanol maser linear polarisation fraction P_L (top), circular polarisation fraction P_V (middle), and linear polarisation angle ψ (bottom) plotted as a function of the propagation angle θ and the rate of stimulated emission. Stars indicate the position of the peak of P_L. Magnetic field strength is 10 mG, thermal velocity width is 1 km s⁻¹ and the hyperfine transitions are indicated in each panel. The panel at the top-left labelled “baseline” indicates a fixed pumping rate equal for all the hyperfine transitions, while all others assume a 10 × preferred pumping for the indicated i → j transition. The results of the simulation performed with other magnetic field strengths are given in Appendix A.