Average projected distance of the distribution of cosmological neighbors as a function of the standard deviation σ_z of their redshift distribution and of the redshift z_src of the target radio source. Upper panel: average projected distance of the distribution of cosmological neighbors of FR Is and FR IIs (black circles) and WATCAT sources (green circles) is plotted as a function of the standard deviation σ_z of their redshift distribution. Lower panel: average projected distance of the distribution of cosmological neighbors of FR Is and FR IIs (gray circles) and WATCAT sources (green circles) plotted as a function of the redshift z_src of the target radio source. In the lower panel, we also show the results as mean values per redshift bin (WATs are green diamonds and FR Is and FR IIs are black circles). The WATs cosmological neighbors are clustered around Mpc. In the redshift bin 0.08–0.09, we observed a large scatter because there are only two sources and they have a large difference in the projected distance of the cosmological neighbors.