Average SFE above a minimum column density contour as a function of column density for the selected CAFFEINE (red) and nearby clouds (green). The shaded areas mark the corresponding uncertainties (cf. Eq. (8) in Sect. 5.1). For the CAFFEINE sample, the red line shows the weighted average of the two SFE estimates. The purple dots indicate averages offormerworks,where the bars show the interquartile range of each cloud sample. For comparison, the blue and black curves represent the two simple models for the SFE (є_ff and filament scenarios – see Sect. 6.1) and a factor 2 uncertainty. See Figs. 7 and 8 for more details on the observed SFEs.