Comparison between the cavity truncation radii reported in Pichardo et al. (2005) (data points), and the empirical formula by Georgakarakos et al. (2024) in Eq. (5) (solid and dashed lines), for different values of q and e_bin. Dashed lines assume e_cav = 0, while solid lines use the information about minimum and maximum cavity radii (R_min, R_max) provided by Pichardo et al. (2005) to attribute a value of the cavity eccentricity e_cav = (1−R_min/R_max)/(1+R_min/R_max), consistent with the percentage shift of the disc centre from the centre of mass reported in Pichardo et al. (2008). The discrepancy between solid lines and squares results in a reduced chi squared ${\tilde{\chi }}^2\sim 1$, assuming a 12% error bar on all data points, and the worst discrepancy is ∼ 15−20% for the case e_bin = 0.