Bias (left) and σ (right) of the uwa, metallicity, A_V, and sSFR retrieved using either spectral indices only, at different S/Ns, or both spectroscopic and photometric information. The solid dark blue, dashed blue, and dash-dotted sky-blue curves show results for S/N = 10, 20, and 30, respectively. For comparison, the red curves show results obtained using both observed magnitudes and spectral indices at S/N = 10. The dashed green line in the left panels indicates zero bias. The results are for the RF algorithm at z = 0.3.