Histograms of uncertainty of stellar age in SPS, as quantified by ﹩{\sigma }_{{\mathrm{log}}_{10}\mathrm{Age}}﹩, which is the 1 − σ width of the posterior distribution of log₁₀ age inferred by fitting the mock spectra with our SPS code BIGS. Different panels are for different E(B − V) and S/Ns, as indicated. In each panel the filled histogram is for the case where E(B − V) is a free parameter and constrained simultaneously with other stellar population properties during the spectral fitting, while the open histogram is for the case where the spectrum being considered is corrected for dust attenuation using our method before the fitting.