Superbubble diameter distributions for the weakly (top) and the strongly (bottom) dissipative model for three different choices of the background density (bg den. in the legends). The size of the bins is 200 pc. Thick lines are for random sampling, thinner lines for optimal sampling, and the thinnest lines in the top panel are for optimal sampling where the background pressure and superbubble destruction by ISM turbulence are taken into account. The minimum near 400 pc for the solid curves is due to the strong acceleration after the first supernova in a superbubble. It is below the data range for the other curves. Large superbubbles are better explained by the weakly dissipative model.