PDFs of velocity dispersion values for 2 kpc heliocentric distance bins for the distance results with (left columns) and without (right columns) the SA prior. The dotted vertical line indicates the GRS velocity resolution (0.21 km s⁻¹). Dotted anddashed histograms show the distribution for distance results obtained without the size-linewidth prior. Percentages in the legend indicate the respective fraction of Gaussian fit components associated with spiral arm and interarm structures.