Feature importance values when using RandomForestClassifier to select quiescent galaxies in the redshift range 0 < z < 0.25. The results in the upper panel are for the case where none of the features have been duplicated. The lower panel shows the feature importance values for the case where five copies of I_E − u have been injected into the dataset prior to model training. The χ axis labels correspond to feature names used by the pipeline after the pre-processing steps outlined in Sect. 4.2 have been applied, and should be self-explanatory (see the caption of Fig. 7. For example, the feature named 'VIS-u_copy1' is a copy of the feature named 'VIS-u', etc.