Correlations between DM, |dDM/dt| and σ_DM in our dataset (panels a–c) and that of Hobbs et al. (2004) (panels d–f). For each panel, we fit a power law of the form y = ax^b to the data and the slope b of this fit is given in each panel, along with its uncertainty. For the correlation between DM and σ_DM, we fit in logspace due to the lack of an uncertainty in y. As it was done by Hobbs et al. (2004), we excluded all pulsars from their sample with |dDM/dt| > 0.01 cm⁻³ pc yr⁻¹.