To determine the dominant electronic scattering processes, we analysed the contribution to the overall scattering rates as a function of energy for the three processes considered in the calculations, viz. acoustic deformation potential (ADP), polar optic phonon (POP) and ionised impurity (IMP) scattering (Figs S10-S15, Section S2.2 in the SI). In most cases, we find that POP scattering appears to make the largest contribution to the rates, with the exception of p-doped Bi 2 SO 2 for which the rates of ADP and POP scattering are comparable. This is similar to the orthorhombic P nma phases of SnS and SnSe. We also examined the anisotropy in the electrical transport properties (Figs S16-S18, Section 2.3 in the SI). In the tetragonal I4/mmm spacegroup, a = b ̸ = c by symmetry, and transport along the a = b and c directions corresponds to transport within and across the layers respectively (c.f. Fig. ). In all three chalcogenides, the σ is largest along the a = b direction and smallest along the c direction for both nand p-type doping, with the largest anisotropy in the p-doped systems. For n-type doping the |S| are predicted to be relatively isotropic, whereas for p-type doping the calculations predict significant anisotropy at n comparable to the intrinsic n-type carrier concentrations but isotropic S at larger n. For p-doped Bi 2 TeO 2 this "crossover" leads to a significant drop in the averaged |S| around n = 10 19 cm -3 . Aside from this the anisotropy in the PFs is dominated by the σ and the S 2 σ are 1.5 -4× larger along the a = b direction with n-type doping and at least an order of magnitude larger with p-type doping.