L([CII])/L_IR versus L([CII]) (left panel) and L_IR (right) for the ALPINE sources and comparison samples where the [C II] line is detected. For the z >  6 sources, taken from the Matthee et al. (2019) sample, we adopt T_d = 45 K for the detections and L_IR upper limits. For galaxies not detected in the dust-continuum, we show their L([CII])/L_IR 3σ lower limit in the left panel as triangles. Right panel: L_IR limits of the ALPINE sources have been replaced by the L_IR values computed from the IRX–β relation, where possible.