Three independent volume-limited samples 〈M_r, z〉=−21, 0.29 (a), 〈M_r, z〉=−20.5, 0.19 (b) and 〈M_r, z〉=−19.5, 0.13 (c) divided into eight SFR sub-samples. A representative uncertainty on individual measurements is indicated by the error bars in each top-left panel. The IMF–SFR relationship is evident in each independent volume-limited sample. The coloured contours are based on the data densities and the ranges of these densities are indicated alongside each colour bar.