Left panel: comparison of He II λ1640 line flux measurements obtained for different He II λ1640 line flux parametrisations. We compare the He II λ1640 line flux measurements of galaxies with an S/N >  3 obtained using an independently fit He II λ1640 single-Gaussian fit with measurements obtained by (1) fitting He II λ1640 using a single Gaussian whose line width was fixed with the other emission lines (diamonds) and (2) a double Gaussian profile whose one-component line width was fixed with the other emission lines (stars). For the double-Gaussian fit, we only consider the nebular component for comparison. Right panel: comparison of the FWHM of [C III]λ1907 with the FWHM of He II λ1640 fit independently of the other nebular emission lines. The solid line denotes x = y and the dashed line denotes x = 2y.