Results with noisy spectroscopy. The panels show the same as in Fig. 6, the example redshift distribution fits plotted here are from different colour groups than the ones shown in Fig. 6. The redshift distributions estimated for colour groups at higher redshift tend to be less smooth with a greater frequency of spurious peaks. The LASSO and ElasticNet regression algorithms have free parameters that can be adjusted to give smoother distributions but at the cost of lower accuracy.