Scatter plot of the HI mass of AMIGA galaxies as a function of their optical luminosities (in B-band). The black points indicate sources detected in HI while grey arrows indicate upper limits. The typical 1σ error ellipse of the data points is shown in the bottom right corner. The heavy blue lines show the regression fits of this work. The solid line corresponds to the full regression model including upper limits, while the dashed line is for the same model but only including detections (mostly hidden behind the solid line). The red dotted line is the ordinary least squares fit for the detections only. The green and orange dashed lines are from HG84 and Dénes et al. (2014).