Comparison of the velocities of the methanol masers and their associated dust clumps. Left: the median methanol maser velocity plotted as a function of the ATLASGAL clump velocity for sources with an association to an ATLASGAL compact source catalogue (CSC) source. The black line is the fitted linear result, with a Spearman’s rank coefficient of r = 0.98 and p-value << 0.0013. Right: distribution of the offsets between the median methanol maser velocities and the molecular line velocities from ATLASGAL. Fitting the distribution with a Gaussian yields a mean of 0.49 ± 0.18 km s⁻¹ and standard deviation of 3.69 ±0.1 km s⁻¹. We use 3σ (11 km s⁻¹) as a confidence threshold to identify outliers.