Histograms of the difference between PNLF and SBF distance moduli. Each panel shows different comparison/calibration samples. Panel a) original sample of 28 galaxies with PNLF and SBF distances from Ciardullo et al. (2002) and Tonry et al. (2001) respectively, with revised Cepheids calibration. Dotted/dashed vertical lines show the mean/median of the difference. Panel b) as in a) but 5 more galaxies with PNLF measurements made after Ciardullo et al. (2002) are added to the sample. Panel c) as b), but more recent ACSFCS and ACSVCS SBF distances are used when available. Panel d) as c), but the correction from Eq. (A.1) by Blakeslee et al. (2010) is included to Tonry et al. (2001) distances.