Outflow velocity of the ionised absorber for our SUBWAYS targets (red filled stars) plotted against their bolometric luminosity. Also plotted are the same quantities as derived in the analysis of the low-z AGN samples of Tombesi et al. (2012, red empty squares) and G13 (blue empty triangles) and in the high-z AGN sample of C21 (black filled circles). The power-law least-squares fit to the combined samples (a total of 49 individual objects and 63 observations) is shown with a solid line. The shaded area represents the uncertainty of the slopes of our fits to the data. Here the outflow velocity is simply described as the absolute value of v_out.