Density distributions for the error-normalized differences between the magnetic field values determined by the Bonn and Potsdam groups for the 134 measurements presented in Fossati et al. (2015) and in this paper. The overlayed lines are for a Gaussian density distribution. Top panel: normalized differences for the ⟨B_z⟩ obtained from hydrogen lines. Bottom panel: normalized differences for the ⟨B_z⟩ obtained from all lines.