The introduction in the Matthiessen's rule of scattering mechanisms on acoustical and polar optical phonons, on ionized impurities, space charge and interband scattering of the light holes fits the experimental data of conductivity and hole mobility by means of successive iterations. The concentrations NA, ND, as well as the contribution of each individual scattering mechanism are estimated. The method is applied in the case of Zn:GaP and natural (undoped) GaSb.