Ratio of the expected flux density extrapolated from other surveys over the flux density as measured in LoLSS as a function of flux density. From top to bottom, the surveys shown are 8C, VLSSr, LoTSS and NVSS. The extrapolated flux density is calculated assuming a spectral index α = −0.78 (each source is a black circle). A ratio of 1 (dotted blue line) means perfect extrapolation of the flux density value. Solid lines are detection limits imposed by the survey depth, the vertical line is due to the LoLSS limit (assumed 1σ = 4 mJy beam⁻¹), the diagonal line is the sensitivity limit of the survey used for comparison. Red crosses are centered on the binned medians and show the standard deviations on the y direction and the bin size in the x direction. Green crosses are the same but assuming a flux-dependent spectral index as found by de Gasperin et al. (2018a). The dark blue lines show the expected dispersion due to the spectral index distribution.