HIMF results from the combined stacking case as a function of the assumed scatter in the M_HI − M_⋆ and for the polynomial model. We show the results for σ = 0 (dotted-dashed black) σ = 0.1 (dashed orange), σ = 0.2 (dotted-dashed green), σ = 0.3 (dotted purple), σ = 0.4 (solid blue), and σ = 0.5 (dashed gray). Bottom: HIMF from the combined stacking assuming a polynomial and an asymmetric scattering (orange diamonds), compared to the fiducial HIMF from this work (blue squares) and the ALFALFA HIMF at z ∼ 0 (dashed green).