Error budget of [X/H] measurements. Left panels show the medians of the absolute values of the three sources of errors (∆_b , ${\text{Δ}}_{T_{\text{eff}}}$, and ∆_{log g}) in the [Fe/H] determination (see Sect. 3.7.1 for the definitions) among our ten target RSGs. Right panels show the medians of the absolute values of the five sources of errors (${{\mathrm{\Delta }}^{\prime }}_{\text{sca\hspace{0.17em}}},{{\mathrm{\Delta }}^{\prime }}_{v_{\text{micro\hspace{0.17em}}}},{{\mathrm{\Delta }}^{\prime }}_{T_{\text{eff\hspace{0.17em}}}},{{\mathrm{\Delta }}^{\prime }}_{\log 𝑔}$, and ∆′_[Fe/H]) in the [X/H] determination other than [Fe/H] (see Sect. 3.7.2 for the definitions).