Mean residuals as a function of spectroscopic or photometric redshift with the SDSS data and the CFHTLS-WIDE data. The results from steps 3 and 4 of our methods with the network Net_P are compared with those produced by data-driven methods from Pasquet et al. (2019), Beck et al. (2016), Treyer et al. (in prep.), and SED fitting using the Le Phare code (Arnouts et al. 1999; Ilbert et al. 2006). The results from step 3 (step 4) are plotted in light red (purple) for comparison in the lower (upper) panels. Steps 1-3 are applied in advance of the calibration by step 4. For consistency with our test samples, 103 305 SdSs galaxies and 10000 CFHTLS-WIDE galaxies in the given redshift ranges are selected from these studies for the plot. We note that we take z_mode (i.e., the redshift at the peak probability) as the point estimates of photometric redshifts, whereas Pasquet et al. (2019) took z_mean (i.e., the probability-weighted mean redshift) and Treyer et al. (in prep.) took z_med¡an (i.e., the median redshift drawn from the probability distribution).