Robustness of the cross-spectra fits. From left to right, we test the scale-independence of the fits for the measured cross-P(k) between the WiggleZ galaxies and the PCA N_fg = 4 cleaned cube (left column), PCAw N_fg = 4 (middle) and mPCA N_L, N_S = 4, 8 (right). Top panels: Reduced χ² for the least-squares analysis as function of the effective scale of the data cube k_eff when excluding from 1 to 3 smallest and highest k-bins from the fit, namely, by removing either large or small-scale information. Bottom panels: Agreement of the amplitudes of the less-information fits with respect to the reference all-k-bins fitted amplitude, through the quantity Δ_amp, that quantifies how many σ away the Ω_H I b_H Ir values are from the reference, indicated in the text for each panel. In all panels, the vertical line shows the corresponding k_eff for the reference all-k-bin analysis for each cleaning method.