Data from SN surveys (Graur et al. 2015, 2017; Botticella et al. 2017). Top panel: Type II SN rates per unit mass (R_SNuM) versus the SFR per unit mass (sSFR), together with a fit for all the data-points (dashed line) and a fit which excludes the two outliers at sSFR ≈ 1.5 × 10⁻¹² yr⁻¹ and 1.5 × 10⁻⁹ yr⁻¹ (dotted line). The fits use the least-squares method on a first degree polynomial in logarithmic space and the error bars are one standard deviation. These data are corrected for the Chabrier (2003) IMF, since the original data follows the Salpeter (1955) IMF. For a constant SFR, L = κψ∫τϕL(m)dm, where L(m)∝m^3.5 is the luminosity of a star with mass m. However, since τ(m)⋅L(m)∝m, it cancels out with κ and makes the SFR independent of the IMF. Since the SN rate is proportional to κ, it is multiplied by a factor κ_Chabrier/κ_Salpeter ≈ 1.38, this correction therefore also multiplies R_SNuM/sSFR by a factor of 1.38. The bottom panel shows a histogram of the R_SNuM/sSFR ratio (with a bin-width of ), and a kernel density estimation (KDE).