Upper left panel: γ-ray luminosity of as a function of total IR luminosity for our sample. The grey solid line represents the best fit to the data (excluding the MW and NGC 3424) and the grey shaded region shows its 68% confidence level. The trend is consistent with those found by previous works. Lower left panel: residuals of the fit, weighted by their standard deviation, as a function of the total IR luminosity. The horizontal dotted lines correspond to ±3 standard deviations. Upper right panel: γ-ray luminosity as a function of SFR. Three fits performed on different data sets are shown: the full data set (cyan solid line); a reduced data set, excluding the MW and NGC 3424( green dashed line); and the BF, excluding all galaxies in the range −0.5 < log Ṁ_∗ < 0.5 (grey dot-dashed line, see text). The grey shaded region shows the 68% confidence level of the BF fit. The red dotted line represents the best fit to the L_γ–L_IR relation presented in the left panel, translated into the SFR–L_γ plane by Eq. (3), with ϵ = 0.79. The latter agrees only marginally with the data or any of the other three fits. Lower right panel: residuals of the BF fit, weighted by their standard deviation, as a function of the SFR. Horizontal dotted lines correspond to ±3 standard deviations.