Relation between r_SFR and the Hi deficiency. Data points are color-coded according to the value of τ_main obtained from the fit. The mean errors bars for each subsample are provided with the red star for the normal galaxy sample and with the red filled circle for the deficient galaxies. The Spearman correlation coefficient ρ of the relation is indicated. Black triangles are the median values in bins of ΔHi−def= 0.2, and the error bars are the standard deviation of the points in each bins. The black filled line is the best linear fit to the data. The black dotted line indicates the adopted threshold used to separate normal from deficient galaxies.