A Robust Method for Estmating the Hubble ParameterShown here is the distribution of absolute magnitude (assuming a fiducial value of the Hubble constant) versus log rotation velocity for a sample of spiral galaxies from the MarkIII survey. The black dots denote a subset of the data for which one may adopt the model of a sharp apparent magnitude limit (applying the robust incompleteness test of Rauzy, 2001), sub-divided into six "bins" of roughly 50 galaxies in each bin. We apply the ROBUST reconstruction procedure of Hendry et al (2001) to the data in each bin, thus making use of Tully-Fisher information in an entirely non-parametric manner, and estimate the Hubble parameter by a comparison of the reconstructed luminosity function in each sub-sample with the inferred absolute magnitude for HST-observed local calibrators of similar rotation velocity and morphology.