Top panel: i-band Tully–Fisher relation. Red and blue dots indicate HRS galaxies with Hα and H I kinematical data. The solid red line indicates the OLS bisector regression to the HRS data. The dotted blue line represents the template I-band TF relation for the nearby galaxy sample of Masters et al. (2006) but using an OSL bisector method (instead of the bivariate method used by those authors). The dashed green line represents the median OSL bisector fit computed from the 100 subsamples of 135 galaxies matching our galaxy luminosity distribution, randomly selected from the Masters et al. (2006) sample. Bottom panel: M_i distributions of the HRS (red) and the Masters et al. (2006) samples M₂₀₀₆ (blue); dotted lines indicate the median value of the corresponding distribution (HRS = −19.67, M₂₀₀₆ = −20.76).