Upper panel: A_{flux ratio} distribution of the H i refined subsample (ΔA_{flux ratio} < 0.05) (N = 166, blue filled histogram), in comparison with that of the H i sample (N = 312, solid line histogram) (see Sect. 3.4). A half-Gaussian fit (red dashed line) to the H i refined subsample is presented. The half-Gaussian curve is characterized by a standard deviation σ = 0.13. Lower panel: the residual of the half-Gaussian fit to the observed A_{flux ratio} distribution for the H i refined subsample.