Relation (Photometric redshifts–Spectroscopic redshifts)/(1 + Spectroscopic redshifts) (Δz) vs. i-band cModel magnitude for a sample of galaxies with both spectroscopic and photometric redshifts in SDSS DR14 (gray dots). The black pluses and black solid line show the dispersion and peak of the Gaussian fitted in each i-band magnitude bin, respectively. There are in total 17 bins. The red dashed lines indicate the model fitted to the dispersions.