Impact of each component on the average spectrum. Top panel, top: average spectrum M₀ and the predicted effect of a variation of q₁ by ±1σ. Bottom: corresponding α₁ vector. Middle panel, top: average spectrum M₀ and the predicted effect of a variation of q₂ by ±1σ. Bottom: corresponding α₂ vector. Bottom panel, top: average spectrum M₀ and the predicted effect of a variation of q₂ by ±1σ. Bottom: corresponding α₂ vector.