Distribution of the difference δμ = μ^vir − μ^z between virial luminosity and concordance cosmology estimates of the distance modulus μ. Top left panel: full cosmo-sample sources uncorrected for Hβ BLUE, and sources with R_[OIII] >  1 (blue). Top right panel: as in the top-left, but with Hβ BLUE excluded. Bottom left panel: as in the top-right but distinguishing sources with R_FeII < 1.5 (green). Bottom right panel: residuals after correction for Hβ BLUE and orientation effects. The distribution of sources with R_[OIII] >  1 (blue) is also shown, as in the top panels.