Error validation for component amplitudes, evaluated from the FFP6 simulation. The upper panel shows histograms of the normalized errors δ = (A_out − A_in) /σ_out for the three foreground components and including all pixels outside the Commander likelihood analysis mask. The lower panel shows histograms of the fractional error f ≡ (A_out − A_in) /A_in for pixels with a foreground detection level above 5σ. No evidence of significant bias is observed for any component, and the uncertainty estimates for the low-frequency and CO components are accurate to about 12%; the thermal dust uncertainty is underestimated by a factor of 2 due to the presence of unmodelled fluctuations.