Integrated radio–SFR relation at 144 MHz. Blue lines indicate the best-fitting relations using a bisector fitting method as fitted in the log–log space. The dashed green line shows the best-fitting linear relation as fitted in linear space. Shaded bands represent the 3σ confidence intervals from the 1000 Monte–Carlo realisations. Panel a: the SFR is calculated from the TIR luminosity; in the panel b: the SFR is calculated using either the hybrid Hα + 24 μm SFR calibration or a 24 μm only calibration. For both SFR calibrations, the radio–SFR relation is clearly non-linear.