Comparison between the VLBI and single dish measurements of flux density and linear polarization. The Stokes I, m _l and EVPA measurements are shown from top to bottom. The VLBI measurements are evaluated at the core of the jet. In the EVPA panel we plot both the original measurements as well as the modified values based on the justification in the text (see Sect. 4.1). In the first panel we also show the integrated Stokes I for the VLBI data sets at 43 GHz for a direct comparison with the single-dish measurements at the same frequency.