Probability density functions of CO luminosities from NGC0628, NGC3627m and M33, the three galaxies for which both HII region and GMC catalogs are available. Results of powerlaw.py (red line) and Maschberger & Kroupa (2009) fit (blue line) along with observational data for NGC0628, NGC3627, and M33 from Rosolowsky et al. (2021) and Corbelli et al. (2017). NGC0628 and NGC3627 are the two PHANGS galaxies for which both the H II region and GMC samples are available. The CO data for M33 are from Druard et al. (2014) and Corbelli et al. (2017). The adopted completeness limits for the fits are the first of the limits given in Table 5 of Rosolowsky et al. (2021) and are shown as a dashed green line and given in Table 2. The error bars are proportional to $1/\sqrt{(N)}$, where N is the number of points in the bin. When no error bar is plotted, it means N = 1.