IRRC (q_TIR) versus redshift for star-forming galaxies. Objects with detections in both the infrared and radio have directly-constrained values of q_TIR and are shown as yellow points. Objects only detected in the radio are upper limits and shown as red triangles. Objects only detected in the infrared are lower limits and shown as blue triangles. A doubly-censored survival analysis has been used to calculate the median q_TIR within redshift bins, indicated by the magenta points. Error bars (smaller than the magenta points here) represent the 1σ dispersion calculated via the bootstrap method. The magenta line shows the power-law fit to these. The black dotted line and grey shaded area are the local value of Bell (2003) (q_TIR(zt0) = 2.64 ± 0.02) and associated spread (0.26), respectively. In the right-hand panel, the q_TIR distribution is shown separately for direct measurements, upper limits and lower limits.