Positions of α.btfr galaxies with respect to the best fit line to the BTFR. The blue datapoints with errorbars represent the α.btfr galaxies, with outliers marked with a red dot (same as Fig. 2). The x- and y-coordinate of each datapoint corresponds respectively to its position along the best fit line to the BTFR and perpendicular to it (refer to Fig. 2). The errorbars are derived by projecting the errors on both the velocity and the baryonic mass onto the direction perpendicular to the fit line.