Histogram of normalized perpendicular distances for α.btfr galaxies. The blue histogram represents the distribution of d_{⊥ ,i}/σ_{⊥ ,i}, which is the perpendicular distance of a α.btfr datapoint from the fit line, normalized by the perpendicular error for the specific datapoint (refer to Fig. 3). The thin dotted line is a standard normal distribution, which is the expected distribution for a zero intrinsic scatter relation.