Mean redshift bias for different configurations of the calibration pipeline, shown as a function of redshift for ten equal-z tomographic bins. The bias is computed relative to the true mean redshifts of the wide-sample n(z) distributions. Violin points represent the distribution of 500 realisations, where violin points with face colour indicate calibration that used MPT-Mock-sample objects for projection and n(z) reconstruction and points with no face colour indicate the projection and reconstruction are done by using deep-sample objects. The grey shaded region indicates the Euclid requirements for n(z) accuracy in weak lensing cosmology. Blue data points represent Scenario A (original Masters et al. 2015 method); orange data points show Scenario B (photo-zs are used to define the tomographic binning); green ones Scenario C (z_obs projection replaced with MPT-Mock-sample objects); red data points show Scenario D (tomographic bin defined by MPT-Mock-sample objects); purple data points are Scenario E (SOM constructed by MPT-Mock-sample objects); brown data points show Scenario F where full calibration is based on MPT-Mock sample. The pink data points correspond to Scenario G, use the per-object photo-z binning introduced in Roster et al. (2026). The data points have been slightly shifted along the x-axis for clarity.