Median prestellar core mass vs. background column density as observed in the Orion B region after correction for incompleteness effects (black triangles, from Könyves et al. 2019), compared to the prediction of the toy model described in Sect. 3 (blue solid line). The error bars correspond to the inter-quartile range in observed masses for each bin of background column density. The two dashed blue lines mark the inter-quartile range expected in the context of the toy model (see Eq. (2)).