Population diagram of CH₃C(O)CH₃ toward Sgr B2(N2). The observed datapoints are shown in black, blue, and orange for the v = 0, v₁₂ = 1, and v₁₇ = 1 states, respectively, while the synthetic populations are shown in red. No correction is applied in panel a. In panel b, the optical depth correction was applied to both the observed and synthetic populations and the contamination by all other species included in the full model was removed from the observed datapoints. The purple line is a linear fit to the observed populations (in linear-logarithmic space).