Ensemble-averaged intensities of the CO 16–15 line (line centre). The circles show the results for ten different realisations of the ensemble as presented in Fig. A.7. The black line gives the mean value of the ten maps, namely (7.6 ± 1.0) K where 1.0 is the standard deviation. The red, dashed line gives the value derived by the probabilistic approach for the same ensemble. Here, the two lines are lying on top of each other (the difference between the two approaches is about 0.004% for the line intensities and about 0.8% for the optical depths which are not shown here).