The typical size of the associations found in a galaxy increases as the relative spatial resolution of the detector is poorer. To use a homogeneous scale, for each galaxy-detector combination we convert the pixel scale into parsecs per pixel. Different symbols indicate different galaxies: IC 1613 (Garcia et al. 2009; Borissova et al. 2004; Ivanov 1996), NGC 6822 (Wilson 1992; Ivanov 1996), M 33 (Wilson 1991), M 31 (Magnier et al. 1993; Ivanov 1996), NGC 300 (Pietrzyński et al. 2001), NGC 7793 (Pietrzyński et al. 2005), and the sample of spiral galaxies of Bresolin et al. (1998).