Top: 1.4 GHz radio luminosity plotted against the IRAS 60 μm luminosity. The vertical dashed line indicates the 90% completeness limit at the median redshift of the main sample. The vertical dotted line indicates the 90% completeness limit of the second sample. The solid line is the Yun et al. (2001) relation. Bottom: histogram of q (1.4 GHz) values, derived using Eq. (8), using only sources with NQ > 1 at 100 μm. The dashed line is a Gaussian distribution with mean and standard deviation set to 2.34 and 0.26 respectively, which are values found by Yun et al. (2001).