Change in the effective number density of the MICE2 cosmic shear sample , caused by the choice of SOM construction parameters and training samples. Each panel shows one tomographic bin from a single realisation of the MICE2 mock KiDS dataset. We separate, in particular, five option selections that cause the most significant change to the observed representation in the SOMs: three different sets of training inputs, and three different spectroscopic dataset constructions. The legend indicates the spectroscopic samples used (KV450-like fiducial setup, without DEEP2, and using a perfect sampling of the photometric data) and/or the input training data (#colours:#magnitudes). The remaining 16 SOM constructions within each of these subsets are shown as the variously coloured histograms. We can see that the construction of the SOM induces a ∼percent level uncertainty on the representation fraction ; the results presented throughout the paper are therefore robust to the construction of our SOM.