Distribution of log(R) versus log(|v|) for the combined S IV sample. Objects analyzed in this work are shown in blue, and objects from Xu et al. (2019) are shown in red. The sample shows a strong negative correlation with a PCC of −0.86; this drops to −0.68 if the lowest velocity outflow is excluded. The black line shows the best-fit log-linear relationship, given by log(R) = −0.87 log(|v|) + 5.58.