Population diagrams of C₂H₅OH (panels a and b) and CH₃OCHO (panels c and d) for Sgr B2(N3). The black points are computed using the integrated intensities of the observed spectrum while the red points are computed using the integrated intensities of our synthetic model. The error bars on the observed data points are 1σ uncertainties on N_u/g_u. No correction is applied in panels a and c, while in panels b and d the optical depth correction has been applied to both the observed and synthetic populations and the contamination from all other species included in the full LTE model has been removed from the observed data points. The blue line is the weighted linear fit to the observed populations.