Cumulative distributions of the absolute fractional flux error (Eq. (11)) redwards of the Lyman-α emission line when predicting spectra with PCA decompositions over a wavelength range extending up to 2000 Å (black solid line) or up to 1600 Å (grey solid line). Median values are similar for the two estimates (black and grey dashed vertical lines respectively). The 90th percentile from the 1600 Å decomposition (dash-dot-dot grey vertical line) is lower than one for the 2000 Å decomposition (dash-dot-dot black vertical line).