Accuracy of fit parameters in the case of spectra with three Gaussian components. The three rows of frames correspond to the one to three component fits. The solid black, blue, and red lines show the median of the parameter estimates as a function of the noise level, and the shaded areas of the same colour show the inter-quartile ranges. The dotted horizontal lines correspond to the true values. In the frames a, d, and g, the light cyan lines show the fraction of cases where AIC preferred fits with the corresponding number components (i.e. one, two, or three). The dashed dark cyan lines are the same after 40 channels without significant emission were excluded, but these overlap almost perfectly with the previous cyan lines.