Distribution of GPZ photometric redshift estimates vs. spectroscopic redshift for the test sample (not included in training in any way) for the three AGN subsamples; optically identified quasars (left panel), X-ray selected AGN (centre panel) and WISE infrared selected AGN (right panel). The number of training sources used (N_train), the number of test sources plotted (N_test) and the corresponding robust scatter for the test sample (σ_NMAD) are shown in the upper left corner of each panel. The plotted contours are linearly spaced in source density.