Scatter in gas depletion time σ(log t_depl) as a function of aperture size for GalA (top) and GalB (bottom). The solid curves are least-squares fits. The red lines are two-parameter fits, and the blue solid curves are three-parameter fits, where the determined parameters and uncertainties are given in the legend. For the red curves t_gas is kept fixed at 25 Myr. For the dashed curves the minimum/maximum parameter values of each fit are used to give an error interval.